Saturday, December 31, 2016
Dennis MacAlistair Ritchie (September 9, 1941 – c. October 12, 2011)[2][3][4][5] was an American computer scientist.[2] He created the C programming language and, with long-time colleague Ken Thompson, the Unix operating system.[2] Ritchie and Thompson received the Turing Award from the ACM in 1983, the Hamming Medal from the IEEE in 1990 and the National Medal of Technology from President Bill Clinton in 1999. Ritchie was the head of Lucent Technologies System Software Research Department when he retired in 2007. He was the "R" in K&R C, and commonly known by his username dmr.
Contents :
1 Personal life
2 Career
3 Views on computing
4 Awards
5 Death
6 Legacy
7 Gallery
8 Notable work
9 References
10 External links
Personal life[edit]
Dennis Ritchie was born in Bronxville, New York. His father was Alistair E. Ritchie, a longtime Bell Labs scientist and co-author of The Design of Switching Circuits on switching circuit theory. Dennis moved with his family to Summit, New Jersey, as a child, where he graduated from Summit High School.[6] He graduated from Harvard University with degrees in physics and applied mathematics.
Career:
Ken Thompson (left) and Dennis Ritchie (right)
Version 7 Unix for the PDP-11, including Dennis Ritchie's home directory: /usr/dmr
In 1967, Ritchie began working at the Bell Labs Computing Sciences Research Center, and in 1968, he defended his PhD thesis on "Program Structure and Computational Complexity" at Harvard under the supervision of Patrick C. Fischer. However, Ritchie never officially received his PhD degree.[7]
Ritchie was best known as the creator of the C programming language, a key developer of the Unix operating system, and co-author of the book The C Programming Language, and was the 'R' in K&R (a common reference to the book's authors Kernighan and Ritchie). Ritchie worked together with Ken Thompson, the scientist credited with writing the original Unix; one of Ritchie's most important contributions to Unix was its porting to different machines and platforms.[8] They were so influential on Research Unix that Doug McIlroy later wrote, "The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed."[9]
The C language is widely used today in application, operating system, and embedded system development, and its influence is seen in most modern programming languages. Unix has also been influential, establishing concepts and principles that are now precepts of computing.
Ritchie has described a 1970s collaboration with James Reeds and Robert Morris on a ciphertext-only attack on the M-209 US cipher machine that could solve messages of at least 2000–2500 letters.[10] Ritchie relates that, after discussions with the NSA, the authors decided not to publish it, as they were told the principle was applicable to machines then still in use by foreign governments.[10]
Contents :
1 Personal life
2 Career
3 Views on computing
4 Awards
5 Death
6 Legacy
7 Gallery
8 Notable work
9 References
10 External links
Personal life[edit]
Dennis Ritchie was born in Bronxville, New York. His father was Alistair E. Ritchie, a longtime Bell Labs scientist and co-author of The Design of Switching Circuits on switching circuit theory. Dennis moved with his family to Summit, New Jersey, as a child, where he graduated from Summit High School.[6] He graduated from Harvard University with degrees in physics and applied mathematics.
Career:
Ken Thompson (left) and Dennis Ritchie (right)
Version 7 Unix for the PDP-11, including Dennis Ritchie's home directory: /usr/dmr
In 1967, Ritchie began working at the Bell Labs Computing Sciences Research Center, and in 1968, he defended his PhD thesis on "Program Structure and Computational Complexity" at Harvard under the supervision of Patrick C. Fischer. However, Ritchie never officially received his PhD degree.[7]
Ritchie was best known as the creator of the C programming language, a key developer of the Unix operating system, and co-author of the book The C Programming Language, and was the 'R' in K&R (a common reference to the book's authors Kernighan and Ritchie). Ritchie worked together with Ken Thompson, the scientist credited with writing the original Unix; one of Ritchie's most important contributions to Unix was its porting to different machines and platforms.[8] They were so influential on Research Unix that Doug McIlroy later wrote, "The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed."[9]
The C language is widely used today in application, operating system, and embedded system development, and its influence is seen in most modern programming languages. Unix has also been influential, establishing concepts and principles that are now precepts of computing.
Ritchie has described a 1970s collaboration with James Reeds and Robert Morris on a ciphertext-only attack on the M-209 US cipher machine that could solve messages of at least 2000–2500 letters.[10] Ritchie relates that, after discussions with the NSA, the authors decided not to publish it, as they were told the principle was applicable to machines then still in use by foreign governments.[10]
C (/'si?/, as in the letter c) is a general-purpose:
imperative computer programming language, supporting structured programming,
lexical variable scope and recursion, while a static type system prevents many unintended operations.
By design, C provides constructs that map efficiently to typical machine instructions,
and therefore it has found lasting use in applications that had formerly been coded in assembly language,
including operating systems,
as well as various application software for computers ranging from supercomputers to embedded systems.
C was originally developed by Dennis Ritchie between 1969 and 1973 at Bell Labs,[5] and used to re-implement the Unix operating system.
[6] It has since become one of the most widely used programming languages of all time,
[7][8] with C compilers from various vendors available for the majority of existing computer architectures and operating systems.
C has been standardized by the American National Standards Institute (ANSI) since 1989 (see ANSI C) and subsequently by the International Organization for Standardization (ISO).
imperative computer programming language, supporting structured programming,
lexical variable scope and recursion, while a static type system prevents many unintended operations.
By design, C provides constructs that map efficiently to typical machine instructions,
and therefore it has found lasting use in applications that had formerly been coded in assembly language,
including operating systems,
as well as various application software for computers ranging from supercomputers to embedded systems.
C was originally developed by Dennis Ritchie between 1969 and 1973 at Bell Labs,[5] and used to re-implement the Unix operating system.
[6] It has since become one of the most widely used programming languages of all time,
[7][8] with C compilers from various vendors available for the majority of existing computer architectures and operating systems.
C has been standardized by the American National Standards Institute (ANSI) since 1989 (see ANSI C) and subsequently by the International Organization for Standardization (ISO).
Awards:
In 1983, Ritchie and Thompson received the Turing Award for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system. Ritchie's Turing Award lecture was titled "Reflections on Software Research".[12] In 1990, both Ritchie and Thompson received the IEEE Richard W. Hamming Medal from the Institute of Electrical and Electronics Engineers (IEEE), "for the origination of the UNIX operating system and the C programming language".[13]
In 1997, both Ritchie and Thompson were made Fellows of the Computer History Museum, "for co-creation of the UNIX operating system, and for development of the C programming language."[14]
On April 21, 1999, Thompson and Ritchie jointly received the National Medal of Technology of 1998 from President Bill Clinton for co-inventing the UNIX operating system and the C programming language which, according to the citation for the medal, "led to enormous advances in computer hardware, software, and networking systems and stimulated growth of an entire industry, thereby enhancing American leadership in the Information Age".[15][16]
In 2005, the Industrial Research Institute awarded Ritchie its Achievement Award in recognition of his contribution to science and technology, and to society generally, with his development of the Unix operating system.[17]
In 2011, Ritchie, along with Thompson, was awarded the Japan Prize for Information and Communications for his work in the development of the Unix operating system.[18]
In 1983, Ritchie and Thompson received the Turing Award for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system. Ritchie's Turing Award lecture was titled "Reflections on Software Research".[12] In 1990, both Ritchie and Thompson received the IEEE Richard W. Hamming Medal from the Institute of Electrical and Electronics Engineers (IEEE), "for the origination of the UNIX operating system and the C programming language".[13]
In 1997, both Ritchie and Thompson were made Fellows of the Computer History Museum, "for co-creation of the UNIX operating system, and for development of the C programming language."[14]
On April 21, 1999, Thompson and Ritchie jointly received the National Medal of Technology of 1998 from President Bill Clinton for co-inventing the UNIX operating system and the C programming language which, according to the citation for the medal, "led to enormous advances in computer hardware, software, and networking systems and stimulated growth of an entire industry, thereby enhancing American leadership in the Information Age".[15][16]
In 2005, the Industrial Research Institute awarded Ritchie its Achievement Award in recognition of his contribution to science and technology, and to society generally, with his development of the Unix operating system.[17]
In 2011, Ritchie, along with Thompson, was awarded the Japan Prize for Information and Communications for his work in the development of the Unix operating system.[18]
Death:
Dennis Ritchie with Doug McIlroy (left) in May 2011
Ritchie was found dead on October 12, 2011, at the age of 70 at his home in Berkeley Heights, New Jersey, where he lived alone.[2] First news of his death came from his former colleague, Rob Pike.[3][4] The cause and exact time of death have not been disclosed.[19] He had been in frail health for several years following treatment for prostate cancer and heart disease.[2][3][20][21][22]
Legacy:
Following Ritchie's death, computer historian Paul E. Ceruzzi stated:[23]
Ritchie was under the radar. His name was not a household name at all, but... if you had a microscope and could look in a computer, you'd see his work everywhere inside.
In an interview shortly after Ritchie's death, long time colleague Brian Kernighan said Ritchie never expected C to be so significant.[24] Kernighan told The New York Times "The tools that Dennis built—and their direct descendants—run pretty much everything today.”[25] Kernighan reminded readers of how important a role C and UNIX had played in the development of later high-profile projects, such as the iPhone.[26][27] Other testimonials to his influence followed.[28][29][30][31]
At his death, one commentator, compared the relative importance of Steve Jobs and Ritchie, concluding, "[Ritchie's] work played a key role in spawning the technological revolution of the last forty years—including technology on which Apple went on to build its fortune."[32] Another commentator said, "Ritchie, on the other hand, invented and co-invented two key software technologies which make up the DNA of effectively every single computer software product we use directly or even indirectly in the modern age. It sounds like a wild claim, but it really is true."[33] Another said, "many in computer science and related fields knew of Ritchie’s importance to the growth and development of, well, everything to do with computing,..."[34]
The Fedora 16 Linux d
Dennis Ritchie with Doug McIlroy (left) in May 2011
Ritchie was found dead on October 12, 2011, at the age of 70 at his home in Berkeley Heights, New Jersey, where he lived alone.[2] First news of his death came from his former colleague, Rob Pike.[3][4] The cause and exact time of death have not been disclosed.[19] He had been in frail health for several years following treatment for prostate cancer and heart disease.[2][3][20][21][22]
Legacy:
Following Ritchie's death, computer historian Paul E. Ceruzzi stated:[23]
Ritchie was under the radar. His name was not a household name at all, but... if you had a microscope and could look in a computer, you'd see his work everywhere inside.
In an interview shortly after Ritchie's death, long time colleague Brian Kernighan said Ritchie never expected C to be so significant.[24] Kernighan told The New York Times "The tools that Dennis built—and their direct descendants—run pretty much everything today.”[25] Kernighan reminded readers of how important a role C and UNIX had played in the development of later high-profile projects, such as the iPhone.[26][27] Other testimonials to his influence followed.[28][29][30][31]
At his death, one commentator, compared the relative importance of Steve Jobs and Ritchie, concluding, "[Ritchie's] work played a key role in spawning the technological revolution of the last forty years—including technology on which Apple went on to build its fortune."[32] Another commentator said, "Ritchie, on the other hand, invented and co-invented two key software technologies which make up the DNA of effectively every single computer software product we use directly or even indirectly in the modern age. It sounds like a wild claim, but it really is true."[33] Another said, "many in computer science and related fields knew of Ritchie’s importance to the growth and development of, well, everything to do with computing,..."[34]
The Fedora 16 Linux d
Like most imperative languages in the ALGOL tradition, C has facilities for structured programming and allows
lexical variable scope and recursion,
while a static type system prevents many unintended operations. In C, all executable code is contained within subroutines,
which are called "functions"
(although not in the strict sense of functional programming).
Function parameters are always passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values.
C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements.
The C language also exhibits the following characteristics:
There is a small, fixed number of keywords, including a full set of flow of control primitives: for, if/else, while, switch,
and do/while. User-defined names are not distinguished from keywords by any kind of sigil.
There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc.
More than one assignment may be performed in a single statement.
Function return values can be ignored when not needed.
Typing is static, but weakly enforced: all data has a type, but implicit conversions may be performed.
Declaration syntax mimics usage context. C has no "define" keyword; instead, a statement beginning with the name of a type is taken as a declaration.
There is no "function" keyword; instead,
a function is indicated by the parentheses of an argument list.
User-defined (typedef) and compound types are possible.
Heterogeneous aggregate data types (struct) allow related data elements to be accessed and assigned as a unit.
Array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects;
they cannot be assigned or compared using single built-in operators. There is no "array" keyword,
in use or definition; instead, square brackets indicate arrays syntactically, for example month[11].
Enumerated types are possible with the enum keyword. They are not tagged, and are freely interconvertible with integers.
Strings are not a separate data type, but are conventionally implemented as null-terminated arrays of characters.
Low-level access to computer memory is possible by converting machine addresses to typed pointers.
Procedures (subroutines not returning values) are a special case of function, with an untyped return type void.
Functions may not be defined within the lexical scope of other functions.
Function and data pointers permit ad hoc run-time polymorphism.
A preprocessor performs macro definition, source code file inclusion, and conditional compilation.
There is a basic form of modularity: files can be compiled separately and linked together, with control over which functions and data objects are visible to other files via static
and extern attributes.
Complex functionality such as I/O, string manipulation, and mathematical functions are consistently delegated to library routines.
While C does not include some features found in some other languages, such as object orientation or garbage collection, such features can be implemented or emulated in C,
often by way of external libraries (e.g., the Boehm garbage collector or the GLib Object System).
Relations to other languages:
Many later languages have borrowed directly or indirectly from C, including C++, D, Go, Rust, Java, JavaScript, Limbo, LPC, C#, Objective-C, Perl, PHP, Python, Swift, Verilog (hardware description language),[4] and Unix's C shell.
These languages have drawn many of their control structures and other basic features from C. Most of them (with Python being the most dramatic exception) are also very syntactically similar to C in general, and they tend to combine
the recognizable expression and statement syntax of C with underlying type systems, data models,
and semantics that can be radically different.
lexical variable scope and recursion,
while a static type system prevents many unintended operations. In C, all executable code is contained within subroutines,
which are called "functions"
(although not in the strict sense of functional programming).
Function parameters are always passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values.
C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements.
The C language also exhibits the following characteristics:
There is a small, fixed number of keywords, including a full set of flow of control primitives: for, if/else, while, switch,
and do/while. User-defined names are not distinguished from keywords by any kind of sigil.
There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc.
More than one assignment may be performed in a single statement.
Function return values can be ignored when not needed.
Typing is static, but weakly enforced: all data has a type, but implicit conversions may be performed.
Declaration syntax mimics usage context. C has no "define" keyword; instead, a statement beginning with the name of a type is taken as a declaration.
There is no "function" keyword; instead,
a function is indicated by the parentheses of an argument list.
User-defined (typedef) and compound types are possible.
Heterogeneous aggregate data types (struct) allow related data elements to be accessed and assigned as a unit.
Array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects;
they cannot be assigned or compared using single built-in operators. There is no "array" keyword,
in use or definition; instead, square brackets indicate arrays syntactically, for example month[11].
Enumerated types are possible with the enum keyword. They are not tagged, and are freely interconvertible with integers.
Strings are not a separate data type, but are conventionally implemented as null-terminated arrays of characters.
Low-level access to computer memory is possible by converting machine addresses to typed pointers.
Procedures (subroutines not returning values) are a special case of function, with an untyped return type void.
Functions may not be defined within the lexical scope of other functions.
Function and data pointers permit ad hoc run-time polymorphism.
A preprocessor performs macro definition, source code file inclusion, and conditional compilation.
There is a basic form of modularity: files can be compiled separately and linked together, with control over which functions and data objects are visible to other files via static
and extern attributes.
Complex functionality such as I/O, string manipulation, and mathematical functions are consistently delegated to library routines.
While C does not include some features found in some other languages, such as object orientation or garbage collection, such features can be implemented or emulated in C,
often by way of external libraries (e.g., the Boehm garbage collector or the GLib Object System).
Relations to other languages:
Many later languages have borrowed directly or indirectly from C, including C++, D, Go, Rust, Java, JavaScript, Limbo, LPC, C#, Objective-C, Perl, PHP, Python, Swift, Verilog (hardware description language),[4] and Unix's C shell.
These languages have drawn many of their control structures and other basic features from C. Most of them (with Python being the most dramatic exception) are also very syntactically similar to C in general, and they tend to combine
the recognizable expression and statement syntax of C with underlying type systems, data models,
and semantics that can be radically different.
History:
Early developments:
Ken Thompson (left) with Dennis
Ritchie (right, the inventor of the C programming language)
The origin of C is closely tied to
the development of the Unix operating system, originally implemented in
assembly language on a PDP-7 by Ritchie and Thompson, incorporating several
ideas from colleagues. Eventually, they decided to port the operating system to
a PDP-11. The original PDP-11 version of Unix was developed in assembly
language. The developers were considering rewriting the system using the B
language, Thompson's simplified version of BCPL.[9] However B's inability to
take advantage of some of the PDP-11's features, notably byte addressability,
led to C. The name of C was chosen simply as the next after B.[10]
The development of C started in
1972 on the PDP-11 Unix system[11] and first appeared in Version 2 Unix.[12]
The language was not initially designed with portability in mind, but soon ran
on different platforms as well: a compiler for the Honeywell 6000 was written
within the first year of C's history, while an IBM System/370 port followed
soon.[1][11]
Also in 1972, a large part of Unix was
rewritten in C.[13] By 1973, with the addition of struct types, the C language
had become powerful enough that most of the Unix's kernel was now in C.
Unix was one of the first operating
system kernels implemented in a language other than assembly. Earlier instances
include the Multics system which was written in PL/I), and Master Control
Program (MCP) for the Burroughs B5000 written in ALGOL in 1961. In around 1977,
Ritchie and Stephen C. Johnson made further changes to the language to
facilitate portability of the Unix operating system. Johnson's Portable C
Compiler served as the basis for several implementations of C on new
platforms.[11]
K&R C:
The cover of the book, The C Programming Language, first
edition by Brian Kernighan and Dennis Ritchie
In 1978, Brian Kernighan and Dennis Ritchie published the
first edition of The C Programming Language.[1] This book, known to C
programmers as "K&R", served for many years as an informal
specification of the language. The version of C that it describes is commonly
referred to as K&R C. The second edition of the book[14] covers the later
ANSI C standard, described below.
K&R introduced several language features:
Standard I/O library
long int data type
unsigned int data type
Compound assignment operators of
the form =op (such as =-) were changed to the form op= (that is, -=) to remove
the semantic ambiguity created by constructs such as i=-10, which had been
interpreted as i =- 10 (decrement i by 10) instead of the possibly intended i =
-10 (let i be -10).
Even after the publication of the
1989 ANSI standard, for many years K&R C was still considered the
"lowest common denominator" to which C programmers restricted
themselves when maximum portability was desired, since many older compilers were
still in use, and because carefully written K&R C code can be legal
Standard C as well.
In early versions of C, only
functions that return types other than int must be declared if used before the
function definition; functions used without prior declaration were presumed to
return type int.
For example:
long some_function();
/* int */ other_function();
/* int */ calling_function()
{
long
test1;
register
/* int */ test2;
test1 =
some_function();
if (test1
> 0)
test2 = 0;
else
test2 = other_function();
return
test2;
}
The int type specifiers which are
commented out could be omitted in K&R C, but are required in later
standards.
Since K&R function declarations
did not include any information about function arguments, function parameter
type checks were not performed, although some compilers would issue a warning
message if a local function was called with the wrong number of arguments, or
if multiple calls to an external function used different numbers or types of arguments.
Separate tools such as Unix's lint utility were developed that (among other
things) could check for consistency of function use across multiple source
files.
In the years following the
publication of K&R C, several features were added to the language,
supported by compilers from AT&T (in particular PCC[15]) and some other
vendors. These included:
void functions (i.e., functions
with no return value)
functions returning struct or union
types (rather than pointers)
assignment for struct data types
enumerated types
The large number of extensions and
lack of agreement on a standard library, together with the language popularity
and the fact that not even the Unix compilers precisely implemented the K&R
specification, led to the necessity of standardization.
ANSI C and ISO C:
Main article: ANSI C
The cover of the book, The C
Programming Language, second edition by Brian Kernighan and Dennis Ritchie
covering ANSI C
During the late 1970s and 1980s,
versions of C were implemented for a wide variety of mainframe computers,
minicomputers, and microcomputers, including the IBM PC, as its popularity
began to increase significantly.
In 1983, the American National
Standards Institute (ANSI) formed a committee, X3J11, to establish a standard
specification of C. X3J11 based the C standard on the Unix implementation;
however, the non-portable portion of the Unix C library was handed off to the
IEEE working group 1003 to become the basis for the 1988 POSIX standard. In
1989, the C standard was ratified as ANSI X3.159-1989 "Programming
Language C". This version of the language is often referred to as ANSI C,
Standard C, or sometimes C89.
In 1990, the ANSI C standard (with
formatting changes) was adopted by the International Organization for
Standardization (ISO) as ISO/IEC 9899:1990, which is sometimes called C90.
Therefore, the terms "C89" and "C90" refer to the same programming
language.
ANSI, like other national standards
bodies, no longer develops the C standard independently, but defers to the
international C standard, maintained by the working group ISO/IEC
JTC1/SC22/WG14. National adoption of an update to the international standard typically
occurs within a year of ISO publication.
One of the aims of the C
standardization process was to produce a superset of K&R C, incorporating
many of the subsequently introduced unofficial features. The standards
committee also included several additional features such as function prototypes
(borrowed from C++), void pointers, support for international character sets
and locales, and preprocessor enhancements. Although the syntax for parameter
declarations was augmented to include the style used in C++, the K&R
interface continued to be permitted, for compatibility with existing source
code.
C89 is supported by current C
compilers, and most C code being written today is based on it. Any program
written only in Standard C and without any hardware-dependent assumptions will
run correctly on any platform with a conforming C implementation, within its
resource limits. Without such precautions, programs may compile only on a
certain platform or with a particular compiler, due, for example, to the use of
non-standard libraries, such as GUI libraries, or to a reliance on compiler- or
platform-specific attributes such as the exact size of data types and byte
endianness.
In cases where code must be
compilable by either standard-conforming or K&R C-based compilers, the
__STDC__ macro can be used to split the code into Standard and K&R sections
to prevent the use on a K&R C-based compiler of features available only in
Standard C.
After the ANSI/ISO standardization
process, the C language specification remained relatively static for several
years. In 1995, Normative Amendment 1 to the 1990 C standard (ISO/IEC
9899/AMD1:1995, known informally as C95) was published, to correct some details
and to add more extensive support for international character sets.[citation needed]
C99:
Main article: C99
The C standard was further revised
in the late 1990s, leading to the publication of ISO/IEC 9899:1999 in 1999,
which is commonly referred to as "C99". It has since been amended
three times by Technical Corrigenda.[16]
C99 introduced several new
features, including inline functions, several new data types (including long
long int and a complex type to represent complex numbers), variable-length
arrays and flexible array members, improved support for IEEE 754 floating point,
support for variadic macros (macros of variable arity), and support for
one-line comments beginning with //, as in BCPL or C++. Many of these had
already been implemented as extensions in several C compilers.
C99 is for the most part backward
compatible with C90, but is stricter in some ways; in particular, a declaration
that lacks a type specifier no longer has int implicitly assumed. A standard
macro __STDC_VERSION__ is defined with value 199901L to indicate that C99
support is available. GCC, Solaris Studio, and other C compilers now support
many or all of the new features of C99. The C compiler in Microsoft Visual C++,
however, implements the C89 standard and those parts of C99 that are required
for compatibility with C++11.[17]
C11:
Main article: C11 (C standard revision)
In 2007, work began on another
revision of the C standard, informally called "C1X" until its
official publication on 2011-12-08. The C standards committee adopted
guidelines to limit the adoption of new features that had not been tested by
existing implementations.
The C11 standard adds numerous new
features to C and the library, including type generic macros, anonymous
structures, improved Unicode support, atomic operations, multi-threading, and
bounds-checked functions. It also makes some portions of the existing C99
library optional, and improves compatibility with C++. The standard macro
__STDC_VERSION__ is defined as 201112L to indicate that C11 support is
available.
Embedded C:
Main article: Embedded C
Historically, embedded C
programming requires nonstandard extensions to the C language in order to
support exotic features such as fixed-point arithmetic, multiple distinct
memory banks, and basic I/O operations.
In 2008, the C Standards Committee
published a technical report extending the C language[18] to address these
issues by providing a common standard for all implementations to adhere to. It
includes a number of features not available in normal C, such as fixed-point
arithmetic, named address spaces, and basic I/O hardware addressing.
Syntax
Main article: C syntax
C has a formal grammar specified by
the C standard.[19] Line endings are generally not significant in C; however,
line boundaries do have significance during the preprocessing phase. Comments
may appear either between the delimiters /* and */, or (since C99) following //
until the end of the line. Comments delimited by /* and */ do not nest, and
these sequences of characters are not interpreted as comment delimiters if they
appear inside string or character literals.[20]
C source files contain declarations
and function definitions. Function definitions, in turn, contain declarations
and statements. Declarations either define new types using keywords such as
struct, union, and enum, or assign types to and perhaps reserve storage for new
variables, usually by writing the type followed by the variable name. Keywords
such as char and int specify built-in types. Sections of code are enclosed in
braces ({ and }, sometimes called "curly brackets") to limit the
scope of declarations and to act as a single statement for control structures.
As an imperative language, C uses
statements to specify actions. The most common statement is an expression
statement, consisting of an expression to be evaluated, followed by a
semicolon; as a side effect of the evaluation, functions may be called and
variables may be assigned new values. To modify the normal sequential execution
of statements, C provides several control-flow statements identified by reserved
keywords. Structured programming is supported by if(-else) conditional
execution and by do-while, while, and for iterative execution (looping). The
for statement has separate initialization, testing, and reinitialization
expressions, any or all of which can be omitted. break and continue can be used
to leave the innermost enclosing loop statement or skip to its
reinitialization. There is also a non-structured goto statement which branches
directly to the designated label within the function. switch selects a case to
be executed based on the value of an integer expression.
Expressions can use a variety of
built-in operators and may contain function calls. The order in which arguments
to functions and operands to most operators are evaluated is unspecified. The
evaluations may even be interleaved. However, all side effects (including
storage to variables) will occur before the next "sequence point";
sequence points include the end of each expression statement, and the entry to
and return from each function call. Sequence points also occur during
evaluation of expressions containing certain operators (&&, ||, ?: and
the comma operator). This permits a high degree of object code optimization by
the compiler, but requires C programmers to take more care to obtain reliable
results than is needed for other programming languages.
Kernighan and Ritchie say in the
Introduction of The C Programming Language: "C, like any other language,
has its blemishes. Some of the operators have the wrong precedence; some parts
of the syntax could be better."[21] The C standard did not attempt to
correct many of these blemishes, because of the impact of such changes on
already existing software.
Character set:
The basic C source character set includes the
following characters:
Lowercase and uppercase letters of
ISO Basic Latin Alphabet: a–z A–Z
Decimal digits: 0–9
Graphic characters: ! " # %
& ' ( ) * + , - . / : ; < = > ? [ \ ] ^ _ { | } ~
Whitespace characters: space,
horizontal tab, vertical tab, form feed, newline
Newline indicates the end of a text
line; it need not correspond to an actual single character, although for
convenience C treats it as one.
Additional multi-byte encoded
characters may be used in string literals, but they are not entirely portable.
The latest C standard (C11) allows multi-national Unicode characters to be
embedded portably within C source text by using \uXXXX or \UXXXXXXXX encoding
(where the X denotes a hexadecimal character), although this feature is not yet
widely implemented.
The basic C execution character set
contains the same characters, along with representations for alert, backspace,
and carriage return. Run-time support for extended character sets has increased
with each revision of the C standard.
Like most imperative languages in the ALGOL tradition, C has facilities for structured programming and allows
lexical variable scope and recursion,
while a static type system prevents many unintended operations. In C, all executable code is contained within subroutines,
which are called "functions"
(although not in the strict sense of functional programming).
Function parameters are always passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values.
C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements.
The C language also exhibits the following characteristics:
There is a small, fixed number of keywords, including a full set of flow of control primitives: for, if/else, while, switch,
and do/while. User-defined names are not distinguished from keywords by any kind of sigil.
There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc.
More than one assignment may be performed in a single statement.
Function return values can be ignored when not needed.
Typing is static, but weakly enforced: all data has a type, but implicit conversions may be performed.
Declaration syntax mimics usage context. C has no "define" keyword; instead, a statement beginning with the name of a type is taken as a declaration.
There is no "function" keyword; instead,
a function is indicated by the parentheses of an argument list.
User-defined (typedef) and compound types are possible.
Heterogeneous aggregate data types (struct) allow related data elements to be accessed and assigned as a unit.
Array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects;
they cannot be assigned or compared using single built-in operators. There is no "array" keyword,
in use or definition; instead, square brackets indicate arrays syntactically, for example month[11].
Enumerated types are possible with the enum keyword. They are not tagged, and are freely interconvertible with integers.
Strings are not a separate data type, but are conventionally implemented as null-terminated arrays of characters.
Low-level access to computer memory is possible by converting machine addresses to typed pointers.
Procedures (subroutines not returning values) are a special case of function, with an untyped return type void.
Functions may not be defined within the lexical scope of other functions.
Function and data pointers permit ad hoc run-time polymorphism.
A preprocessor performs macro definition, source code file inclusion, and conditional compilation.
There is a basic form of modularity: files can be compiled separately and linked together, with control over which functions and data objects are visible to other files via static
and extern attributes.
Complex functionality such as I/O, string manipulation, and mathematical functions are consistently delegated to library routines.
While C does not include some features found in some other languages, such as object orientation or garbage collection, such features can be implemented or emulated in C,
often by way of external libraries (e.g., the Boehm garbage collector or the GLib Object System).
Relations to other languages[edit]
Many later languages have borrowed directly or indirectly from C, including C++, D, Go, Rust, Java, JavaScript, Limbo, LPC, C#, Objective-C, Perl, PHP, Python, Swift, Verilog (hardware description language),[4] and Unix's C shell.
These languages have drawn many of their control structures and other basic features from C. Most of them (with Python being the most dramatic exception) are also very syntactically similar to C in general, and they tend to combine
the recognizable expression and statement syntax of C with underlying type systems, data models,
and semantics that can be radically different.
lexical variable scope and recursion,
while a static type system prevents many unintended operations. In C, all executable code is contained within subroutines,
which are called "functions"
(although not in the strict sense of functional programming).
Function parameters are always passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values.
C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements.
The C language also exhibits the following characteristics:
There is a small, fixed number of keywords, including a full set of flow of control primitives: for, if/else, while, switch,
and do/while. User-defined names are not distinguished from keywords by any kind of sigil.
There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc.
More than one assignment may be performed in a single statement.
Function return values can be ignored when not needed.
Typing is static, but weakly enforced: all data has a type, but implicit conversions may be performed.
Declaration syntax mimics usage context. C has no "define" keyword; instead, a statement beginning with the name of a type is taken as a declaration.
There is no "function" keyword; instead,
a function is indicated by the parentheses of an argument list.
User-defined (typedef) and compound types are possible.
Heterogeneous aggregate data types (struct) allow related data elements to be accessed and assigned as a unit.
Array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects;
they cannot be assigned or compared using single built-in operators. There is no "array" keyword,
in use or definition; instead, square brackets indicate arrays syntactically, for example month[11].
Enumerated types are possible with the enum keyword. They are not tagged, and are freely interconvertible with integers.
Strings are not a separate data type, but are conventionally implemented as null-terminated arrays of characters.
Low-level access to computer memory is possible by converting machine addresses to typed pointers.
Procedures (subroutines not returning values) are a special case of function, with an untyped return type void.
Functions may not be defined within the lexical scope of other functions.
Function and data pointers permit ad hoc run-time polymorphism.
A preprocessor performs macro definition, source code file inclusion, and conditional compilation.
There is a basic form of modularity: files can be compiled separately and linked together, with control over which functions and data objects are visible to other files via static
and extern attributes.
Complex functionality such as I/O, string manipulation, and mathematical functions are consistently delegated to library routines.
While C does not include some features found in some other languages, such as object orientation or garbage collection, such features can be implemented or emulated in C,
often by way of external libraries (e.g., the Boehm garbage collector or the GLib Object System).
Relations to other languages[edit]
Many later languages have borrowed directly or indirectly from C, including C++, D, Go, Rust, Java, JavaScript, Limbo, LPC, C#, Objective-C, Perl, PHP, Python, Swift, Verilog (hardware description language),[4] and Unix's C shell.
These languages have drawn many of their control structures and other basic features from C. Most of them (with Python being the most dramatic exception) are also very syntactically similar to C in general, and they tend to combine
the recognizable expression and statement syntax of C with underlying type systems, data models,
and semantics that can be radically different.
History:
Early developments:
Ken Thompson (left) with Dennis
Ritchie (right, the inventor of the C programming language)
The origin of C is closely tied to
the development of the Unix operating system, originally implemented in
assembly language on a PDP-7 by Ritchie and Thompson, incorporating several
ideas from colleagues. Eventually, they decided to port the operating system to
a PDP-11. The original PDP-11 version of Unix was developed in assembly
language. The developers were considering rewriting the system using the B
language, Thompson's simplified version of BCPL.[9] However B's inability to
take advantage of some of the PDP-11's features, notably byte addressability,
led to C. The name of C was chosen simply as the next after B.[10]
The development of C started in
1972 on the PDP-11 Unix system[11] and first appeared in Version 2 Unix.[12]
The language was not initially designed with portability in mind, but soon ran
on different platforms as well: a compiler for the Honeywell 6000 was written
within the first year of C's history, while an IBM System/370 port followed
soon.[1][11]
Also in 1972, a large part of Unix was
rewritten in C.[13] By 1973, with the addition of struct types, the C language
had become powerful enough that most of the Unix's kernel was now in C.
Unix was one of the first operating
system kernels implemented in a language other than assembly. Earlier instances
include the Multics system which was written in PL/I), and Master Control
Program (MCP) for the Burroughs B5000 written in ALGOL in 1961. In around 1977,
Ritchie and Stephen C. Johnson made further changes to the language to
facilitate portability of the Unix operating system. Johnson's Portable C
Compiler served as the basis for several implementations of C on new
platforms.[11]
K&R C:
The cover of the book, The C Programming Language, first
edition by Brian Kernighan and Dennis Ritchie
In 1978, Brian Kernighan and Dennis Ritchie published the
first edition of The C Programming Language.[1] This book, known to C
programmers as "K&R", served for many years as an informal
specification of the language. The version of C that it describes is commonly
referred to as K&R C. The second edition of the book[14] covers the later
ANSI C standard, described below.
K&R introduced several language features:
Standard I/O library
long int data type
unsigned int data type
Compound assignment operators of
the form =op (such as =-) were changed to the form op= (that is, -=) to remove
the semantic ambiguity created by constructs such as i=-10, which had been
interpreted as i =- 10 (decrement i by 10) instead of the possibly intended i =
-10 (let i be -10).
Even after the publication of the
1989 ANSI standard, for many years K&R C was still considered the
"lowest common denominator" to which C programmers restricted
themselves when maximum portability was desired, since many older compilers were
still in use, and because carefully written K&R C code can be legal
Standard C as well.
In early versions of C, only
functions that return types other than int must be declared if used before the
function definition; functions used without prior declaration were presumed to
return type int.
For example:
long some_function();
/* int */ other_function();
/* int */ calling_function()
{
long
test1;
register
/* int */ test2;
test1 =
some_function();
if (test1
> 0)
test2 = 0;
else
test2 = other_function();
return
test2;
}
The int type specifiers which are
commented out could be omitted in K&R C, but are required in later
standards.
Since K&R function declarations
did not include any information about function arguments, function parameter
type checks were not performed, although some compilers would issue a warning
message if a local function was called with the wrong number of arguments, or
if multiple calls to an external function used different numbers or types of arguments.
Separate tools such as Unix's lint utility were developed that (among other
things) could check for consistency of function use across multiple source
files.
In the years following the
publication of K&R C, several features were added to the language,
supported by compilers from AT&T (in particular PCC[15]) and some other
vendors. These included:
void functions (i.e., functions
with no return value)
functions returning struct or union
types (rather than pointers)
assignment for struct data types
enumerated types
The large number of extensions and
lack of agreement on a standard library, together with the language popularity
and the fact that not even the Unix compilers precisely implemented the K&R
specification, led to the necessity of standardization.
ANSI C and ISO C:
Main article: ANSI C
The cover of the book, The C
Programming Language, second edition by Brian Kernighan and Dennis Ritchie
covering ANSI C
During the late 1970s and 1980s,
versions of C were implemented for a wide variety of mainframe computers,
minicomputers, and microcomputers, including the IBM PC, as its popularity
began to increase significantly.
In 1983, the American National
Standards Institute (ANSI) formed a committee, X3J11, to establish a standard
specification of C. X3J11 based the C standard on the Unix implementation;
however, the non-portable portion of the Unix C library was handed off to the
IEEE working group 1003 to become the basis for the 1988 POSIX standard. In
1989, the C standard was ratified as ANSI X3.159-1989 "Programming
Language C". This version of the language is often referred to as ANSI C,
Standard C, or sometimes C89.
In 1990, the ANSI C standard (with
formatting changes) was adopted by the International Organization for
Standardization (ISO) as ISO/IEC 9899:1990, which is sometimes called C90.
Therefore, the terms "C89" and "C90" refer to the same programming
language.
ANSI, like other national standards
bodies, no longer develops the C standard independently, but defers to the
international C standard, maintained by the working group ISO/IEC
JTC1/SC22/WG14. National adoption of an update to the international standard typically
occurs within a year of ISO publication.
One of the aims of the C
standardization process was to produce a superset of K&R C, incorporating
many of the subsequently introduced unofficial features. The standards
committee also included several additional features such as function prototypes
(borrowed from C++), void pointers, support for international character sets
and locales, and preprocessor enhancements. Although the syntax for parameter
declarations was augmented to include the style used in C++, the K&R
interface continued to be permitted, for compatibility with existing source
code.
C89 is supported by current C
compilers, and most C code being written today is based on it. Any program
written only in Standard C and without any hardware-dependent assumptions will
run correctly on any platform with a conforming C implementation, within its
resource limits. Without such precautions, programs may compile only on a
certain platform or with a particular compiler, due, for example, to the use of
non-standard libraries, such as GUI libraries, or to a reliance on compiler- or
platform-specific attributes such as the exact size of data types and byte
endianness.
In cases where code must be
compilable by either standard-conforming or K&R C-based compilers, the
__STDC__ macro can be used to split the code into Standard and K&R sections
to prevent the use on a K&R C-based compiler of features available only in
Standard C.
After the ANSI/ISO standardization
process, the C language specification remained relatively static for several
years. In 1995, Normative Amendment 1 to the 1990 C standard (ISO/IEC
9899/AMD1:1995, known informally as C95) was published, to correct some details
and to add more extensive support for international character sets.[citation needed]
C99:
Main article: C99
The C standard was further revised
in the late 1990s, leading to the publication of ISO/IEC 9899:1999 in 1999,
which is commonly referred to as "C99". It has since been amended
three times by Technical Corrigenda.[16]
C99 introduced several new
features, including inline functions, several new data types (including long
long int and a complex type to represent complex numbers), variable-length
arrays and flexible array members, improved support for IEEE 754 floating point,
support for variadic macros (macros of variable arity), and support for
one-line comments beginning with //, as in BCPL or C++. Many of these had
already been implemented as extensions in several C compilers.
C99 is for the most part backward
compatible with C90, but is stricter in some ways; in particular, a declaration
that lacks a type specifier no longer has int implicitly assumed. A standard
macro __STDC_VERSION__ is defined with value 199901L to indicate that C99
support is available. GCC, Solaris Studio, and other C compilers now support
many or all of the new features of C99. The C compiler in Microsoft Visual C++,
however, implements the C89 standard and those parts of C99 that are required
for compatibility with C++11.[17]
C11:
Main article: C11 (C standard revision)
In 2007, work began on another
revision of the C standard, informally called "C1X" until its
official publication on 2011-12-08. The C standards committee adopted
guidelines to limit the adoption of new features that had not been tested by
existing implementations.
The C11 standard adds numerous new
features to C and the library, including type generic macros, anonymous
structures, improved Unicode support, atomic operations, multi-threading, and
bounds-checked functions. It also makes some portions of the existing C99
library optional, and improves compatibility with C++. The standard macro
__STDC_VERSION__ is defined as 201112L to indicate that C11 support is
available.
Embedded C:
Main article: Embedded C
Historically, embedded C
programming requires nonstandard extensions to the C language in order to
support exotic features such as fixed-point arithmetic, multiple distinct
memory banks, and basic I/O operations.
In 2008, the C Standards Committee
published a technical report extending the C language[18] to address these
issues by providing a common standard for all implementations to adhere to. It
includes a number of features not available in normal C, such as fixed-point
arithmetic, named address spaces, and basic I/O hardware addressing.
Syntax
Main article: C syntax
C has a formal grammar specified by
the C standard.[19] Line endings are generally not significant in C; however,
line boundaries do have significance during the preprocessing phase. Comments
may appear either between the delimiters /* and */, or (since C99) following //
until the end of the line. Comments delimited by /* and */ do not nest, and
these sequences of characters are not interpreted as comment delimiters if they
appear inside string or character literals.[20]
C source files contain declarations
and function definitions. Function definitions, in turn, contain declarations
and statements. Declarations either define new types using keywords such as
struct, union, and enum, or assign types to and perhaps reserve storage for new
variables, usually by writing the type followed by the variable name. Keywords
such as char and int specify built-in types. Sections of code are enclosed in
braces ({ and }, sometimes called "curly brackets") to limit the
scope of declarations and to act as a single statement for control structures.
As an imperative language, C uses
statements to specify actions. The most common statement is an expression
statement, consisting of an expression to be evaluated, followed by a
semicolon; as a side effect of the evaluation, functions may be called and
variables may be assigned new values. To modify the normal sequential execution
of statements, C provides several control-flow statements identified by reserved
keywords. Structured programming is supported by if(-else) conditional
execution and by do-while, while, and for iterative execution (looping). The
for statement has separate initialization, testing, and reinitialization
expressions, any or all of which can be omitted. break and continue can be used
to leave the innermost enclosing loop statement or skip to its
reinitialization. There is also a non-structured goto statement which branches
directly to the designated label within the function. switch selects a case to
be executed based on the value of an integer expression.
Expressions can use a variety of
built-in operators and may contain function calls. The order in which arguments
to functions and operands to most operators are evaluated is unspecified. The
evaluations may even be interleaved. However, all side effects (including
storage to variables) will occur before the next "sequence point";
sequence points include the end of each expression statement, and the entry to
and return from each function call. Sequence points also occur during
evaluation of expressions containing certain operators (&&, ||, ?: and
the comma operator). This permits a high degree of object code optimization by
the compiler, but requires C programmers to take more care to obtain reliable
results than is needed for other programming languages.
Kernighan and Ritchie say in the
Introduction of The C Programming Language: "C, like any other language,
has its blemishes. Some of the operators have the wrong precedence; some parts
of the syntax could be better."[21] The C standard did not attempt to
correct many of these blemishes, because of the impact of such changes on
already existing software.
Character set:
The basic C source character set includes the
following characters:
Lowercase and uppercase letters of
ISO Basic Latin Alphabet: a–z A–Z
Decimal digits: 0–9
Graphic characters: ! " # %
& ' ( ) * + , - . / : ; < = > ? [ \ ] ^ _ { | } ~
Whitespace characters: space,
horizontal tab, vertical tab, form feed, newline
Newline indicates the end of a text
line; it need not correspond to an actual single character, although for
convenience C treats it as one.
Additional multi-byte encoded
characters may be used in string literals, but they are not entirely portable.
The latest C standard (C11) allows multi-national Unicode characters to be
embedded portably within C source text by using \uXXXX or \UXXXXXXXX encoding
(where the X denotes a hexadecimal character), although this feature is not yet
widely implemented.
The basic C execution character set
contains the same characters, along with representations for alert, backspace,
and carriage return. Run-time support for extended character sets has increased
with each revision of the C standard.
References:
Jump up to: a b c d e Kernighan, Brian W.; Ritchie, Dennis M. (February 1978). The C Programming Language (1st ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110163-3. Regarded by many to be the authoritative reference on C.
Jump up ^ Ritchie (1993): "Thompson had made a brief attempt to produce a system coded in an early version of C—before structures—in 1972, but gave up the effort."
Jump up ^ Ritchie (1993): "The scheme of type composition adopted by C owes considerable debt to Algol 68, although it did not, perhaps, emerge in a form that Algol's adherents would approve of."^ Jump up to: a b "Verilog HDL (and C)" (PDF). The Research School of Computer Science at the Australian National University. 2010-06-03. Retrieved 2013-08-19. 1980s: ; Verilog first introduced ; Verilog inspired by the C programming languageJump up ^ Ritchie (1993)
Jump up ^ Lawlis, Patricia K. (August 1997). "Guidelines for Choosing a Computer Language: Support for the Visionary Organization". Ada Information Clearinghouse. Retrieved 18 July 2006.Jump up ^ "Programming Language Popularity". 2009. Retrieved 16 January 2009.
Jump up ^ "TIOBE Programming Community Index". 2009. Retrieved 6 May 2009.Jump up ^ Ritchie, Dennis M. (March 1993). "The Development of the C Language". ACM SIGPLAN Notices. 28 (3): 201–208. doi:10.1145/155360.155580.Jump up ^ Ulf Bilting & Jan Skansholm "Vägen till C" (Swedish) meaning "The Road to C", third edition, Studentlitteratur, year 2000, page 3. ISBN 91-44-01468-6.
^ Jump up to: a b c Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System". Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. Retrieved 16 December 2012. (Note: this reference is an OCR scan of the original, and contains an OCR glitch rendering "IBM 370" as "IBM 310".)Jump up ^ McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. p. 10. 139.Jump up ^ Stallings, William. "Operating Systems: Internals and Design Principles" 5th ed, page 91. Pearson Education, Inc. 2005.^ Jump up to: a b Kernighan, Brian W.; Ritchie, Dennis M. (March 1988). The C Programming Language (2nd ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110362-8.Jump up ^ Stroustrup, Bjarne (2002). Sibling rivalry: C and C++ (PDF) (Report). AT&T Labs.Jump up ^ "JTC1/SC22/WG14 – C". Home page. ISO/IEC. Retrieved 2 June 2011.Jump up ^ Andrew Binstock (October 12, 2011). "Interview with Herb Sutter". Dr. Dobbs. Retrieved September 7, 2013.Jump up ^ "TR 18037: Embedded C" (PDF). ISO / IEC. Retrieved 26 July 2011.Jump up ^ Harbison, Samuel P.; Steele, Guy L. (2002). C: A Reference Manual (5th ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-089592-X. Contains a BNF grammar for C.Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. p. 192. ISBN 7 302 02412 X.Jump up ^ Page 3 of the original K&R[1]Jump up ^ ISO/IEC 9899:201x (ISO C11) Committee DraftJump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. pp. 192, 259. ISBN 7 302 02412 X.Jump up ^ "10 Common Programming Mistakes in C++". Cs.ucr.edu. Retrieved 26 June 2009.Jump up ^ Schultz, Thomas (2004). C and the 8051 (3rd ed.). Otsego, MI: PageFree Publishing Inc. p. 20. ISBN 1-58961-237-X. Retrieved 10 February 2012.Jump up ^ Page 6 of the original K&R[1]^ Jump up to: a b c d e f g Klemens, Ben (2013). 21st Century C. O'Reilly Media. ISBN 1-4493-2714-1.Jump up ^ Feuer, Alan R.; Gehani, Narain H. (March 1982). "Comparison of the Programming Languages C and Pascal". ACM Computing Surveys. 14 (1): 73–92. doi:10.1145/356869.356872. (subscription required (help)).Jump up ^ Page 122 of K&R2[14]Jump up ^ For example, gcc provides _FORTIFY_SOURCE. "Security Features: Compile Time Buffer Checks (FORTIFY_SOURCE)". fedoraproject.org. Retrieved 2012-08-05.Jump up ^ Raymond, Eric S. (11 October 1996). The New Hacker's Dictionary (3rd ed.). MIT Press. p. 432. ISBN 978-0-262-68092-9. Retrieved 5 August 2012.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 6.23". Retrieved March 6, 2013.Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 7.28". Retrieved March 6, 2013.Jump up ^ "Man Page for lint (freebsd Section 1)". unix.com. 2001-05-24. Retrieved 2014-07-15.Jump up ^ McMillan, Robert (2013-08-01). "Is Java Losing Its Mojo?". Wired.Jump up ^ Dr. Dobb's Sourcebook. U.S.A.: Miller Freeman, Inc. November–December 1995.Jump up ^ "Using C for CGI Programming". linuxjournal.com. 1 March 2005. Retrieved 4 January 2010.Jump up ^ Stroustrup, Bjarne (1993). "A History of C++: 1979-1991" (PDF). Retrieved 9 June 2011.
Jump up ^ Ritchie (1993): "Thompson had made a brief attempt to produce a system coded in an early version of C—before structures—in 1972, but gave up the effort."
Jump up ^ Ritchie (1993): "The scheme of type composition adopted by C owes considerable debt to Algol 68, although it did not, perhaps, emerge in a form that Algol's adherents would approve of."^ Jump up to: a b "Verilog HDL (and C)" (PDF). The Research School of Computer Science at the Australian National University. 2010-06-03. Retrieved 2013-08-19. 1980s: ; Verilog first introduced ; Verilog inspired by the C programming languageJump up ^ Ritchie (1993)
Jump up ^ Lawlis, Patricia K. (August 1997). "Guidelines for Choosing a Computer Language: Support for the Visionary Organization". Ada Information Clearinghouse. Retrieved 18 July 2006.Jump up ^ "Programming Language Popularity". 2009. Retrieved 16 January 2009.
Jump up ^ "TIOBE Programming Community Index". 2009. Retrieved 6 May 2009.Jump up ^ Ritchie, Dennis M. (March 1993). "The Development of the C Language". ACM SIGPLAN Notices. 28 (3): 201–208. doi:10.1145/155360.155580.Jump up ^ Ulf Bilting & Jan Skansholm "Vägen till C" (Swedish) meaning "The Road to C", third edition, Studentlitteratur, year 2000, page 3. ISBN 91-44-01468-6.
^ Jump up to: a b c Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System". Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. Retrieved 16 December 2012. (Note: this reference is an OCR scan of the original, and contains an OCR glitch rendering "IBM 370" as "IBM 310".)Jump up ^ McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. p. 10. 139.Jump up ^ Stallings, William. "Operating Systems: Internals and Design Principles" 5th ed, page 91. Pearson Education, Inc. 2005.^ Jump up to: a b Kernighan, Brian W.; Ritchie, Dennis M. (March 1988). The C Programming Language (2nd ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110362-8.Jump up ^ Stroustrup, Bjarne (2002). Sibling rivalry: C and C++ (PDF) (Report). AT&T Labs.Jump up ^ "JTC1/SC22/WG14 – C". Home page. ISO/IEC. Retrieved 2 June 2011.Jump up ^ Andrew Binstock (October 12, 2011). "Interview with Herb Sutter". Dr. Dobbs. Retrieved September 7, 2013.Jump up ^ "TR 18037: Embedded C" (PDF). ISO / IEC. Retrieved 26 July 2011.Jump up ^ Harbison, Samuel P.; Steele, Guy L. (2002). C: A Reference Manual (5th ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-089592-X. Contains a BNF grammar for C.Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. p. 192. ISBN 7 302 02412 X.Jump up ^ Page 3 of the original K&R[1]Jump up ^ ISO/IEC 9899:201x (ISO C11) Committee DraftJump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. pp. 192, 259. ISBN 7 302 02412 X.Jump up ^ "10 Common Programming Mistakes in C++". Cs.ucr.edu. Retrieved 26 June 2009.Jump up ^ Schultz, Thomas (2004). C and the 8051 (3rd ed.). Otsego, MI: PageFree Publishing Inc. p. 20. ISBN 1-58961-237-X. Retrieved 10 February 2012.Jump up ^ Page 6 of the original K&R[1]^ Jump up to: a b c d e f g Klemens, Ben (2013). 21st Century C. O'Reilly Media. ISBN 1-4493-2714-1.Jump up ^ Feuer, Alan R.; Gehani, Narain H. (March 1982). "Comparison of the Programming Languages C and Pascal". ACM Computing Surveys. 14 (1): 73–92. doi:10.1145/356869.356872. (subscription required (help)).Jump up ^ Page 122 of K&R2[14]Jump up ^ For example, gcc provides _FORTIFY_SOURCE. "Security Features: Compile Time Buffer Checks (FORTIFY_SOURCE)". fedoraproject.org. Retrieved 2012-08-05.Jump up ^ Raymond, Eric S. (11 October 1996). The New Hacker's Dictionary (3rd ed.). MIT Press. p. 432. ISBN 978-0-262-68092-9. Retrieved 5 August 2012.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 6.23". Retrieved March 6, 2013.Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 7.28". Retrieved March 6, 2013.Jump up ^ "Man Page for lint (freebsd Section 1)". unix.com. 2001-05-24. Retrieved 2014-07-15.Jump up ^ McMillan, Robert (2013-08-01). "Is Java Losing Its Mojo?". Wired.Jump up ^ Dr. Dobb's Sourcebook. U.S.A.: Miller Freeman, Inc. November–December 1995.Jump up ^ "Using C for CGI Programming". linuxjournal.com. 1 March 2005. Retrieved 4 January 2010.Jump up ^ Stroustrup, Bjarne (1993). "A History of C++: 1979-1991" (PDF). Retrieved 9 June 2011.
References:
^ Jump up to: a b c d e Kernighan, Brian W.; Ritchie, Dennis M. (February 1978). The C Programming Language (1st ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110163-3. Regarded by many to be the authoritative reference on C.
Jump up ^ Ritchie (1993): "Thompson had made a brief attempt to produce a system coded in an early version of C—before structures—in 1972, but gave up the effort."
Jump up ^ Ritchie (1993): "The scheme of type composition adopted by C owes considerable debt to Algol 68, although it did not, perhaps, emerge in a form that Algol's adherents would approve of."
^ Jump up to: a b "Verilog HDL (and C)" (PDF). The Research School of Computer Science at the Australian National University. 2010-06-03. Retrieved 2013-08-19. 1980s: ; Verilog first introduced ; Verilog inspired by the C programming language
Jump up ^ Ritchie (1993)
Jump up ^ Lawlis, Patricia K. (August 1997). "Guidelines for Choosing a Computer Language: Support for the Visionary Organization". Ada Information Clearinghouse. Retrieved 18 July 2006.
Jump up ^ "Programming Language Popularity". 2009. Retrieved 16 January 2009.
Jump up ^ "TIOBE Programming Community Index". 2009. Retrieved 6 May 2009.
Jump up ^ Ritchie, Dennis M. (March 1993). "The Development of the C Language". ACM SIGPLAN Notices. 28 (3): 201–208. doi:10.1145/155360.155580.
Jump up ^ Ulf Bilting & Jan Skansholm "Vägen till C" (Swedish) meaning "The Road to C", third edition, Studentlitteratur, year 2000, page 3. ISBN 91-44-01468-6.
^ Jump up to: a b c Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System". Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. Retrieved 16 December 2012. (Note: this reference is an OCR scan of the original, and contains an OCR glitch rendering "IBM 370" as "IBM 310".)
Jump up ^ McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. p. 10. 139.
Jump up ^ Stallings, William. "Operating Systems: Internals and Design Principles" 5th ed, page 91. Pearson Education, Inc. 2005.
^ Jump up to: a b Kernighan, Brian W.; Ritchie, Dennis M. (March 1988). The C Programming Language (2nd ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110362-8.
Jump up ^ Stroustrup, Bjarne (2002). Sibling rivalry: C and C++ (PDF) (Report). AT&T Labs.
Jump up ^ "JTC1/SC22/WG14 – C". Home page. ISO/IEC. Retrieved 2 June 2011.
Jump up ^ Andrew Binstock (October 12, 2011). "Interview with Herb Sutter". Dr. Dobbs. Retrieved September 7, 2013.
Jump up ^ "TR 18037: Embedded C" (PDF). ISO / IEC. Retrieved 26 July 2011.
Jump up ^ Harbison, Samuel P.; Steele, Guy L. (2002). C: A Reference Manual (5th ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-089592-X. Contains a BNF grammar for C.
Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. p. 192. ISBN 7 302 02412 X.
Jump up ^ Page 3 of the original K&R[1]
Jump up ^ ISO/IEC 9899:201x (ISO C11) Committee Draft
Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. pp. 192, 259. ISBN 7 302 02412 X.
Jump up ^ "10 Common Programming Mistakes in C++". Cs.ucr.edu. Retrieved 26 June 2009.
Jump up ^ Schultz, Thomas (2004). C and the 8051 (3rd ed.). Otsego, MI: PageFree Publishing Inc. p. 20. ISBN 1-58961-237-X. Retrieved 10 February 2012.
Jump up ^ Page 6 of the original K&R[1]
^ Jump up to: a b c d e f g Klemens, Ben (2013). 21st Century C. O'Reilly Media. ISBN 1-4493-2714-1.
Jump up ^ Feuer, Alan R.; Gehani, Narain H. (March 1982). "Comparison of the Programming Languages C and Pascal". ACM Computing Surveys. 14 (1): 73–92. doi:10.1145/356869.356872. (subscription required (help)).
Jump up ^ Page 122 of K&R2[14]
Jump up ^ For example, gcc provides _FORTIFY_SOURCE. "Security Features: Compile Time Buffer Checks (FORTIFY_SOURCE)". fedoraproject.org. Retrieved 2012-08-05.
Jump up ^ Raymond, Eric S. (11 October 1996). The New Hacker's Dictionary (3rd ed.). MIT Press. p. 432. ISBN 978-0-262-68092-9. Retrieved 5 August 2012.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 6.23". Retrieved March 6, 2013.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 7.28". Retrieved March 6, 2013.
Jump up ^ "Man Page for lint (freebsd Section 1)". unix.com. 2001-05-24. Retrieved 2014-07-15.
Jump up ^ McMillan, Robert (2013-08-01). "Is Java Losing Its Mojo?". Wired.
Jump up ^ Dr. Dobb's Sourcebook. U.S.A.: Miller Freeman, Inc. November–December 1995.
Jump up ^ "Using C for CGI Programming". linuxjournal.com. 1 March 2005. Retrieved 4 January 2010.
Jump up ^ Stroustrup, Bjarne (1993). "A History of C++: 1979-1991" (PDF). Retrieved 9 June 2011.
^ Jump up to: a b c d e Kernighan, Brian W.; Ritchie, Dennis M. (February 1978). The C Programming Language (1st ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110163-3. Regarded by many to be the authoritative reference on C.
Jump up ^ Ritchie (1993): "Thompson had made a brief attempt to produce a system coded in an early version of C—before structures—in 1972, but gave up the effort."
Jump up ^ Ritchie (1993): "The scheme of type composition adopted by C owes considerable debt to Algol 68, although it did not, perhaps, emerge in a form that Algol's adherents would approve of."
^ Jump up to: a b "Verilog HDL (and C)" (PDF). The Research School of Computer Science at the Australian National University. 2010-06-03. Retrieved 2013-08-19. 1980s: ; Verilog first introduced ; Verilog inspired by the C programming language
Jump up ^ Ritchie (1993)
Jump up ^ Lawlis, Patricia K. (August 1997). "Guidelines for Choosing a Computer Language: Support for the Visionary Organization". Ada Information Clearinghouse. Retrieved 18 July 2006.
Jump up ^ "Programming Language Popularity". 2009. Retrieved 16 January 2009.
Jump up ^ "TIOBE Programming Community Index". 2009. Retrieved 6 May 2009.
Jump up ^ Ritchie, Dennis M. (March 1993). "The Development of the C Language". ACM SIGPLAN Notices. 28 (3): 201–208. doi:10.1145/155360.155580.
Jump up ^ Ulf Bilting & Jan Skansholm "Vägen till C" (Swedish) meaning "The Road to C", third edition, Studentlitteratur, year 2000, page 3. ISBN 91-44-01468-6.
^ Jump up to: a b c Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System". Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. Retrieved 16 December 2012. (Note: this reference is an OCR scan of the original, and contains an OCR glitch rendering "IBM 370" as "IBM 310".)
Jump up ^ McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. p. 10. 139.
Jump up ^ Stallings, William. "Operating Systems: Internals and Design Principles" 5th ed, page 91. Pearson Education, Inc. 2005.
^ Jump up to: a b Kernighan, Brian W.; Ritchie, Dennis M. (March 1988). The C Programming Language (2nd ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-110362-8.
Jump up ^ Stroustrup, Bjarne (2002). Sibling rivalry: C and C++ (PDF) (Report). AT&T Labs.
Jump up ^ "JTC1/SC22/WG14 – C". Home page. ISO/IEC. Retrieved 2 June 2011.
Jump up ^ Andrew Binstock (October 12, 2011). "Interview with Herb Sutter". Dr. Dobbs. Retrieved September 7, 2013.
Jump up ^ "TR 18037: Embedded C" (PDF). ISO / IEC. Retrieved 26 July 2011.
Jump up ^ Harbison, Samuel P.; Steele, Guy L. (2002). C: A Reference Manual (5th ed.). Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-089592-X. Contains a BNF grammar for C.
Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. p. 192. ISBN 7 302 02412 X.
Jump up ^ Page 3 of the original K&R[1]
Jump up ^ ISO/IEC 9899:201x (ISO C11) Committee Draft
Jump up ^ Kernighan, Brian W.; Ritchie, Dennis M. (1996). The C Programming Language (2nd ed.). Prentice Hall. pp. 192, 259. ISBN 7 302 02412 X.
Jump up ^ "10 Common Programming Mistakes in C++". Cs.ucr.edu. Retrieved 26 June 2009.
Jump up ^ Schultz, Thomas (2004). C and the 8051 (3rd ed.). Otsego, MI: PageFree Publishing Inc. p. 20. ISBN 1-58961-237-X. Retrieved 10 February 2012.
Jump up ^ Page 6 of the original K&R[1]
^ Jump up to: a b c d e f g Klemens, Ben (2013). 21st Century C. O'Reilly Media. ISBN 1-4493-2714-1.
Jump up ^ Feuer, Alan R.; Gehani, Narain H. (March 1982). "Comparison of the Programming Languages C and Pascal". ACM Computing Surveys. 14 (1): 73–92. doi:10.1145/356869.356872. (subscription required (help)).
Jump up ^ Page 122 of K&R2[14]
Jump up ^ For example, gcc provides _FORTIFY_SOURCE. "Security Features: Compile Time Buffer Checks (FORTIFY_SOURCE)". fedoraproject.org. Retrieved 2012-08-05.
Jump up ^ Raymond, Eric S. (11 October 1996). The New Hacker's Dictionary (3rd ed.). MIT Press. p. 432. ISBN 978-0-262-68092-9. Retrieved 5 August 2012.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 6.23". Retrieved March 6, 2013.
Jump up ^ Summit, Steve. "comp.lang.c Frequently Asked Questions 7.28". Retrieved March 6, 2013.
Jump up ^ "Man Page for lint (freebsd Section 1)". unix.com. 2001-05-24. Retrieved 2014-07-15.
Jump up ^ McMillan, Robert (2013-08-01). "Is Java Losing Its Mojo?". Wired.
Jump up ^ Dr. Dobb's Sourcebook. U.S.A.: Miller Freeman, Inc. November–December 1995.
Jump up ^ "Using C for CGI Programming". linuxjournal.com. 1 March 2005. Retrieved 4 January 2010.
Jump up ^ Stroustrup, Bjarne (1993). "A History of C++: 1979-1991" (PDF). Retrieved 9 June 2011.
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