The C standard library or libc is the
standard library for the
C programming language, as specified in the
ISO C standard.
ISO
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
/IEC
The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
(2018). '' ISO/IEC 9899:2018(E): Programming Languages - C §7'' Starting from the original
ANSI C
ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and th ...
standard, it was developed at the same time as
the C library POSIX specification, which is a superset of it. Since ANSI C was adopted by the
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...
,
the C standard library is also called the ISO C library.
The C standard library provides
macros,
type definitions and functions for tasks such as
string handling, mathematical computations, input/output processing,
memory management
Memory management is a form of resource management applied to computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when ...
, and several other
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
services.
Application programming interface
Header files
The
application programming interface
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how t ...
(API) of the C standard library is declared in a number of
header file
Many programming languages and other computer files have a directive, often called include (sometimes copy or import), that causes the contents of the specified file to be inserted into the original file. These included files are called copybooks ...
s. Each header file contains one or more function declarations, data type definitions, and macros.
After a long period of stability, three new header files (
iso646.h
,
wchar.h
, and
wctype.h
) were added with ''Normative Addendum 1'' (NA1), an addition to the C Standard ratified in 1995. Six more header files (
complex.h
,
fenv.h
,
inttypes.h
,
stdbool.h
,
stdint.h
, and
tgmath.h
) were added with
C99
C99 (previously known as C9X) is an informal name for ISO/IEC 9899:1999, a past version of the C programming language standard. It extends the previous version ( C90) with new features for the language and the standard library, and helps impl ...
, a revision to the C Standard published in 1999, and five more files (
stdalign.h
,
stdatomic.h
,
stdnoreturn.h
,
threads.h
, and
uchar.h
) with
C11 C11, C.XI, C-11 or C.11 may refer to:
Transport
* C-11 Fleetster, a 1920s American light transport aircraft for use of the United States Assistant Secretary of War
* Fokker C.XI, a 1935 Dutch reconnaissance seaplane
* LET C-11, a license-build var ...
in 2011. In total, there are now 29 header files:
Three of the header files (
complex.h
,
stdatomic.h
, and
threads.h
) are conditional features that implementations are not required to support.
The
POSIX
The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inter ...
standard added several nonstandard C headers for Unix-specific functionality. Many have found their way to other architectures. Examples include
fcntl.h
and
unistd.h
In the C and C++ programming languages, unistd.h is the name of the header file that provides access to the POSIX operating system API. It is defined by the POSIX.1 standard, the base of the Single Unix Specification, and should therefore be a ...
. A number of other groups are using other nonstandard headers – the
GNU C Library
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by ...
has
alloca.h
, and HP
OpenVMS has the
va_count()
function.
Documentation
On Unix-like systems, the authoritative documentation of the actually implemented API is provided in the form of
man page
A man page (short for manual page) is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs (including library and system calls), formal standards and conventions, and e ...
s. On most systems, man pages on standard library functions are in section 3; section 7 may contain some more generic pages on underlying concepts (e.g.
man 7 math_error
in
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
).
Implementations
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
systems typically have a C library in
shared library
In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subro ...
form, but the header files (and compiler toolchain) may be absent from an installation so C development may not be possible. The C library is considered part of the operating system on Unix-like systems. The C functions, including the ISO C standard ones, are widely used by programs, and are regarded as if they were not only an implementation of something in the C language, but also ''de facto'' part of the operating system interface. Unix-like operating systems generally cannot function if the C library is erased. This is true for applications which are dynamically as opposed to statically linked. Further, the kernel itself (at least in the case of Linux) operates independently of any libraries.
On Microsoft Windows, the core system dynamic libraries (
DLLs) provide an implementation of the C standard library for the
Microsoft Visual C++ compiler v6.0; the C standard library for newer versions of the Microsoft Visual C++ compiler is provided by each compiler individually, as well as ''redistributable'' packages. Compiled applications written in C are either statically linked with a C library, or linked to a dynamic version of the library that is shipped with these applications, rather than relied upon to be present on the targeted systems. Functions in a compiler's C library are not regarded as interfaces to Microsoft Windows.
Many other implementations exist, provided with both various operating systems and C compilers. Some of the popular implementations are the following:
* The
BSD libc
The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard.ISO/IEC (2018). '' ISO/IEC 9899:2018(E): Programming Languages - C §7'' Starting from the original ANSI C standard, it was d ...
, various implementations distributed with
BSD
The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berk ...
-derived operating systems
*
GNU C Library
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by ...
(glibc), used in
GNU Hurd
GNU Hurd is a collection of microkernel servers written as part of GNU, for the GNU Mach microkernel. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, and ...
,
GNU/kFreeBSD and
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
*
Microsoft C run-time library, part of
Microsoft Visual C++
Microsoft Visual C++ (MSVC) is a compiler for the C, C++ and C++/CX programming languages by Microsoft. MSVC is proprietary software; it was originally a standalone product but later became a part of Visual Studio and made available in both tri ...
*
dietlibc
dietlibc is a C standard library released under the GNU General Public License Version 2, and proprietary licenses are also available. It was developed with the help of about 100 volunteers by Felix von Leitner with the goal to compile and lin ...
, an alternative small implementation of the C standard library (MMU-less)
*
μClibc, a C standard library for embedded
μClinux
μClinux is a variation of the Linux kernel, previously maintained as a fork, that targets microcontrollers without a memory management unit (MMU). It was integrated into the mainline kernel as of 2.5.46; the project continues to develop patc ...
systems (MMU-less)
**
uclibc-ng, an embedded C library, fork of μClibc, still maintained, with
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical a ...
(MMU) support
*
Newlib
Newlib is a C standard library implementation intended for use on embedded systems. It is a conglomeration of several library parts, all under free software licenses that make them easily usable on embedded products.
It was created by Cygnus S ...
, a C standard library for embedded systems (MMU-less) and used in the
Cygwin GNU distribution for Windows
*
klibc
In computing, klibc is a minimalistic subset of the standard C library developed by H. Peter Anvin. It was developed mainly to be used during the Linux startup process, and it is part of the early user space, i.e. components used during kernel ...
, primarily for booting Linux systems
*
musl
musl is a C standard library intended for operating systems based on the Linux kernel, released under the MIT License. It was developed by Rich Felker with the goal to write a clean, efficient and standards-conformant libc implementation.
O ...
, another lightweight C standard library implementation for Linux systems
*
Bionic
Bionics or biologically inspired engineering is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology.
The word ''bionic'', coined by Jack E. Steele in August 1 ...
, originally developed by Google for the Android embedded system operating system, derived from BSD libc
picolibc developed by
Keith Packard
Keith Packard (born April 16, 1963) is a software developer, best known for his work on the X Window System.
Packard is responsible for many X extensions and technical papers on X. He has been heavily involved in the development of X since the ...
, targeting small embedded systems with limited RAM, based on code from
Newlib
Newlib is a C standard library implementation intended for use on embedded systems. It is a conglomeration of several library parts, all under free software licenses that make them easily usable on embedded products.
It was created by Cygnus S ...
an
AVR Libc
Compiler built-in functions
Some compilers (for example,
GCC) provide built-in versions of many of the functions in the C standard library; that is, the implementations of the functions are written into the compiled
object file
An object file is a computer file containing object code, that is, machine code output of an assembler or compiler. The object code is usually relocatable, and not usually directly executable. There are various formats for object files, and the ...
, and the program calls the built-in versions instead of the functions in the C library
shared object
In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subro ...
file. This reduces function-call overhead, especially if function calls are replaced with
inline variants, and allows other forms of
optimization
Mathematical optimization (alternatively spelled ''optimisation'') or mathematical programming is the selection of a best element, with regard to some criterion, from some set of available alternatives. It is generally divided into two subfi ...
(as the compiler knows the
control-flow
In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''imp ...
characteristics of the built-in variants), but may cause confusion when debugging (for example, the built-in versions cannot be replaced with
instrumented variants).
However, the built-in functions must behave like ordinary functions in accordance with ISO C. The main implication is that the program must be able to create a pointer to these functions by taking their address, and invoke the function by means of that pointer. If two pointers to the same function are derived in two different translation units in the program, these two pointers must compare equal; that is, the address comes by resolving the name of the function, which has external (program-wide) linkage.
Linking, libm
Under FreeBSD and glibc, some functions such as sin() are not linked in by default and are instead bundled in the mathematical library
libm
C mathematical operations are a group of functions in the standard library of the C programming language implementing basic mathematical functions. All functions use floating-point numbers in one manner or another. Different C standards provide d ...
. If any of them are used, the linker must be given the directive
-lm
. POSIX requires that the c99 compiler supports
-lm
, and that the functions declared in the headers
math.h
,
complex.h
, and
fenv.h
are available for linking if
-lm
is specified, but does not specify if the functions are linked by default. musl satisfies this requirement by putting everything into a single libc library and providing an empty libm.
Detection
According to the C standard the macro
__STDC_HOSTED__
shall be defined to 1 if the implementation is hosted. A hosted implementation has all the headers specified by the C standard. An implementation can also be ''freestanding'' which means that these headers will not be present. If an implementation is ''freestanding'', it shall define
__STDC_HOSTED__
to 0.
Problems and workarounds
Buffer overflow vulnerabilities
Some functions in the C standard library have been notorious for having
buffer overflow
In information security and programming, a buffer overflow, or buffer overrun, is an anomaly whereby a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.
Buffers are areas of memo ...
vulnerabilities and generally encouraging buggy programming ever since their adoption. The most criticized items are:
*
string-manipulation routines, including
strcpy()
and
strcat()
, for lack of
bounds checking
In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as ...
and possible buffer overflows if the bounds aren't checked manually;
* string routines in general, for
side-effects
In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...
, encouraging irresponsible buffer usage, not always guaranteeing valid
null-terminated output, linear length calculation;
*
printf
The printf format string is a control parameter used by a class of functions in the input/output libraries of C and many other programming languages. The string is written in a simple template language: characters are usually copied literal ...
()
family of routines, for spoiling the
execution stack when the format string doesn't match the arguments given. This fundamental flaw created an entire class of attacks:
format string attacks;
*
gets()
and
scanf
A scanf format string (''scan f''ormatted) is a control parameter used in various functions to specify the layout of an input string. The functions can then divide the string and translate into values of appropriate data types. String scannin ...
()
family of I/O routines, for lack of (either any or easy) input length checking.
Except the extreme case with
gets()
, all the security vulnerabilities can be avoided by introducing auxiliary code to perform memory management, bounds checking, input checking, etc. This is often done in the form of wrappers that make standard library functions safer and easier to use. This dates back to as early as ''
The Practice of Programming'' book by B. Kernighan and R. Pike where the authors commonly use wrappers that print error messages and quit the program if an error occurs.
The ISO C committee published Technical reports TR 24731-1 and is working on TR 24731-2 to propose adoption of some functions with bounds checking and automatic buffer allocation, correspondingly. The former has met severe criticism with some praise, the latter received mixed responses. Despite this, TR 24731-1 has been implemented into Microsoft's C standard library and its compiler issues warnings when using old "insecure" functions.
Threading problems, vulnerability to race conditions
The
strerror()
routine is criticized for being
thread unsafe and otherwise vulnerable to
race condition
A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is Sequential logic, dependent on the sequence or timing of other uncontrollable events. It becomes a software ...
s.
Error handling
The error handling of the functions in the C standard library is not consistent and sometimes confusing. According to the Linux manual page
math_error
, "The current (version 2.8) situation under glibc is messy. Most (but not all) functions raise exceptions on errors. Some also set ''errno''. A few functions set ''errno'', but don't raise an exception. A very few functions do neither."
Standardization
The original
C language
C (''pronounced like the letter c'') is a general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities o ...
provided no built-in functions such as I/O operations, unlike traditional languages such as
COBOL and
Fortran. Over time, user communities of C shared ideas and implementations of what is now called C standard libraries. Many of these ideas were incorporated eventually into the definition of the standardized C language.
Both
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...
and C were created at
AT&T's Bell Laboratories in the late 1960s and early 1970s. During the 1970s the C language became increasingly popular. Many universities and organizations began creating their own variants of the language for their own projects. By the beginning of the 1980s compatibility problems between the various C implementations became apparent. In 1983 the
American National Standards Institute (ANSI) formed a committee to establish a standard specification of C known as "
ANSI C
ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and th ...
". This work culminated in the creation of the so-called C89 standard in 1989. Part of the resulting standard was a set of
software libraries
In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subro ...
called the ANSI C standard library.
POSIX standard library
POSIX
The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inter ...
, as well as
SUS, specify a number of routines that should be available over and above those in the basic C standard library. The POSIX specification includes header files for, among other uses,
multi-threading,
networking, and
regular expression
A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...
s. These are often implemented alongside the C standard library functionality, with varying degrees of closeness. For example,
glibc
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by ...
implements functions such as
fork
In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tine (structural), tines with which one ...
within
libc.so
, but before
NPTL The Native POSIX Thread Library (NPTL) is an implementation of the POSIX Threads specification for the Linux operating system.
History
Before the 2.6 version of the Linux kernel, processes were the schedulable entities, and there were no special f ...
was merged into glibc it constituted a separate library with its own linker flag argument. Often, this POSIX-specified functionality will be regarded as part of the library; the basic C library may be identified as the ANSI or
ISO
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
C library.
BSD libc
BSD libc is a superset of the POSIX standard library supported by the C libraries included with
BSD
The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berk ...
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
s such as
FreeBSD,
NetBSD,
OpenBSD and
macOS
macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
. BSD libc has some extensions that are not defined in the original standard, many of which first appeared in 1994's
4.4BSD The History of the Berkeley Software Distribution begins in the 1970s.
1BSD (PDP-11)
The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify a ...
release (the first to be largely developed after the first standard was issued in 1989). Some of the extensions of BSD libc are:
*
sys/tree.h
contains an implementation of
red–black tree and
splay tree
*
sys/queue.h
implementations of
Linked list,
queues,
tail queue, etc.
*
fgetln()
defined in
stdio.h
. This can be used to read a file line by line.
*
fts.h
contains some functions to traverse a file hierarchy
*
db.h
some functions to connect to the
Berkeley DB
Berkeley DB (BDB) is an unmaintained embedded database software library for key/value data, historically significant in open source software. Berkeley DB is written in C with API bindings for many other programming languages. BDB stores arbitr ...
*
strlcat()
and
strlcpy()
secure alternatives for
strncat()
and
strncpy()
*
err.h
contains some functions to print formatted error messages
*
vis.h
contains the
vis()
function. This function is used to display non-printable characters in a visual format.
The C standard library in other languages
Some languages include the functionality of the standard C library in their own libraries. The library may be adapted to better suit the language's structure, but the
operational semantics
Operational semantics is a category of formal programming language semantics in which certain desired properties of a program, such as correctness, safety or security, are verified by constructing proofs from logical statements about its execut ...
are kept similar. The
C++
C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
language, for example, includes the functionality of the C standard library in the
namespace
In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified.
Namespaces ...
std
(e.g.,
std::printf
,
std::atoi
,
std::feof
), in header files with similar names to the C ones (
cstdio
,
cmath
,
cstdlib
, etc.). Other languages that take similar approaches are
D,
Perl
Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offic ...
,
Ruby
A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...
and the main implementation of
Python
Python may refer to:
Snakes
* Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia
** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia
* Python (mythology), a mythical serpent
Computing
* Python (pro ...
known as
CPython
CPython is the reference implementation of the Python programming language. Written in C and Python, CPython is the default and most widely used implementation of the Python language.
CPython can be defined as both an interpreter and a compi ...
. In Python 2, for example, the built-in file objects are defined as "implemented using C's
stdio
package", so that the available operations (open, read, write, etc.) are expected to have the same behavior as the corresponding C functions.
Rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...
has a crate called which allows several C functions, structs, and other type definitions to be used.
Comparison to standard libraries of other languages
The C standard library is small compared to the standard libraries of some other languages. The C library provides a basic set of mathematical functions, string manipulation,
type conversions, and file and console-based I/O. It does not include a standard set of "
container types" like the
C++
C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
Standard Template Library
The Standard Template Library (STL) is a software library originally designed by Alexander Stepanov for the C++ programming language that influenced many parts of the C++ Standard Library. It provides four components called ''algorithms'', '' ...
, let alone the complete
graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inst ...
(GUI) toolkits, networking tools, and profusion of other functionality that
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...
and the
.NET Framework
The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
provide as standard. The main advantage of the small standard library is that providing a working ISO C environment is much easier than it is with other languages, and consequently porting C to a new platform is comparatively easy.
See also
*
C++ Standard Library
The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard. ISO/IEC (2018). '' ISO/IEC 9899:2018(E): Programming Languages - C §7'' Starting from the original ANSI C standard, it was ...
Notes
References
Further reading
*
External links
The C Library Reference Guide* Microsof
Universal C runtime routines by categoryon MSDN
* NetBS
C libraries manual an
full C library sourceManual pages for the original C standard libraries in Unix
{{DEFAULTSORT:C Standard Library
C (programming language)