1intro(3) Library Functions Manual intro(3)
2
6 intro - introduction to library functions
7
9 Section 3 of the manual describes all library functions excluding the
10 library functions (system call wrappers) described in Section 2, which
11 implement system calls.
12 Many of the functions described in the section are part of the Standard
14 C Library (libc). Some functions are part of other libraries (e.g.,
15 the math library, libm, or the real-time library, librt) in which case
16 the manual page will indicate the linker option needed to link against
17 the required library (e.g., -lm and -lrt, respectively, for the afore‐
18 mentioned libraries).
19 In some cases, the programmer must define a feature test macro in order
21 to obtain the declaration of a function from the header file specified
22 in the man page SYNOPSIS section. (Where required, these feature test
23 macros must be defined before including any header files.) In such
24 cases, the required macro is described in the man page. For further
25 information on feature test macros, see feature_test_macros(7).
26 Subsections
28 Section 3 of this manual is organized into subsections that reflect the
29 complex structure of the standard C library and its many implementa‐
30 tions:
31 • 3const
33 • 3head
35 • 3type
37 This difficult history frequently makes it a poor example to follow in
39 design, implementation, and presentation.
40 Ideally, a library for the C language is designed such that each header
42 file presents the interface to a coherent software module. It provides
43 a small number of function declarations and exposes only data types and
44 constants that are required for use of those functions. Together,
45 these are termed an API or application program interface. Types and
46 constants to be shared among multiple APIs should be placed in header
47 files that declare no functions. This organization permits a C library
48 module to be documented concisely with one header file per manual page.
49 Such an approach improves the readability and accessibility of library
50 documentation, and thereby the usability of the software.
51
53 Certain terms and abbreviations are used to indicate UNIX variants and
54 standards to which calls in this section conform. See standards(7).
55
57 Authors and copyright conditions
58 Look at the header of the manual page source for the author(s) and
59 copyright conditions. Note that these can be different from page to
60 page!
61
63 intro(2), errno(3), capabilities(7), credentials(7), environ(7), fea‐
64 ture_test_macros(7), libc(7), math_error(7), path_resolution(7),
65 pthreads(7), signal(7), standards(7), system_data_types(7)
66Linux man-pages 6.04 2023-02-05 intro(3)