The relationship between standard C function library and POSIX function library __ function

The C POSIX Library is a specification of a C standard library for POSIX systems. It is developed at the same time as the ANSI C standard. Some effort is made to make POSIX compatible with standard C; POSIX includes additional functions to those introduced in standard C.

Word: The POSIX library function is a superset of the C standard library function. 1 standard C library

<assert.h> Contains The Assert macro, used to assist with detecting logical and other errors of bugs in de
Bugging versions of a program.
<complex.h> C99 A Set of functions for manipulating complex numbers. <ctype.h> defines set of functions used to classify characters by their types or to convert between and Lower case in a way this is independent of the used character set (typically ASCII or one of its extensions, although Impl
Ementations utilizing EBCDIC are also known).
<errno.h> for testing error codes reported by library functions.
<fenv.h> C99 defines a set of functions for controlling floating-point environment. <float.h> defines macro constants specifying implementation-specific properties of floating-point
ary.
<inttypes.h> C99 defines exact width integer types. <iso646.h> NA1 defines several macros that implement alternative to express ways several. For programThe Ming in ISO 646 variant character sets.
<limits.h> defines macro constants specifying the Implementation-specific properties of the integer types.
<locale.h> defines localization functions.
<math.h> defines common mathematical functions.
<setjmp.h> declares the macros setjmp and longjmp which are for used.
<signal.h> defines signal handling functions.
<stdalign.h> C11 for querying and specifying the alignment of objects.
<stdarg.h> for accessing a varying number of arguments passed to functions.
<stdatomic.h> C11 for atomic operations on data shared between threads.
<stdbool.h> C99 defines a Boolean data type.
<stddef.h> defines several useful types and macros.
<stdint.h> C99 defines exact width integer types. <stdio.h> defines core input and output functions <stdlib.h> defines numeric conversion functions, Pseudo-Random numbers generation Functions, memory allocation, Process Control functions <stdnoreturn.h> C11 for specifying non-returning.
<string.h> defines string handling functions.
<tgmath.h> C99 defines type-generic mathematical functions.
<threads.h> C11 defines functions for managing multiple threads as AS and mutexes condition. <time.h> defines date and time handling functions <uchar.h> C11 Types and functions for manipulating
Unicode characters.
<wchar.h> NA1 defines wide string handling functions.  <wctype.h> NA1 defines set of functions used to classify wide characters from their types or to convert between and lower case

2 POSIX libraries (excluding standard C libraries)

<aio.h> asynchronous input and output Issue 5 <arpa/inet.h> functions for manipulating numeric IP address
ES (part of Berkeley sockets) Issue 6 <assert.h> Verify assumptions??
<complex.h> complex arithmetic, C mathematical functions?? <cpio.h> Magic numbers for the CPIO archive format Issue 3 <dirent.h> allows the opening and listing of
Directories Issue 2 <dlfcn.h> Dynamic linking Issue 5 <errno.h> retrieving Error number?? <fcntl.h> File opening, locking and other operations Issue 1 <fenv.h> floating-point environment (FPE),
C mathematical functions??
<float.h> floating-point types, the C data types?? <fmtmsg.h> Message Display Structures Issue 4 <fnmatch.h> Filename matching Issue 4 <ftw.h> File tre  E traversal Issue 1 <glob.h> Pathname "globbing" (pattern-matching) Issue 4 <grp.h> User Group information and control Issue 1 <iconv.h> codeset Conversion Facility Issue 4 <inttypes.h> Fixed sized integer types, C data types??
<iso646.h> alternative spellings, C alternative tokens?? <langinfo.h> Language Information constants–builds on C localization functions Issue 2 <libgen.h> Pathna
Me manipulation Issue 4 <limits.h> implementation-defined constants, C data types??
<locale.h> Category macros, C localization functions??
<math.h> mathematical declarations, C mathematical functions??     <monetary.h> String formatting of monetary units Issue 4 <mqueue.h> message Queue Issue 5 <ndbm.h> NDBM Database Operations Issue 4 <net/if.h> Listing of local network interfaces Issue 6 <netdb.h> Tr Anslating protocol and host names into numeric addresses (part of Berkeley sockets) Issue 6 <netinet/in.h> Define S Internet protocol and address family (part of Berkeley sockets) Issue 6;netinet/tcp.h> Additional TCP Control Options (part of Berkeley sockets) Issue 6 <nl_types.h> Localization  Message catalog Functions Issue 2 <poll.h> Asynchronous file descriptor multiplexing Issue 4 <pthread.h> Defines an APIs for creating and manipulating POSIX threads Issue 5 <pwd.h> passwd (user information) Access and Co Ntrol Issue 1 <regex.h> Regular expression matching Issue 4 <sched.h> Execution scheduling Issue 5 & Lt;search.h> Search Tables Issue 1 <semaphore.h> POSIX semaphores Issue 5 <setjmp.h> Stack environ
ment declarations??
<signal.h> signals, C signal handling??
<spawn.h> Process spawning Issue 6 <stdarg.h> Handle Variable Argument List??
<stdbool.h> Boolean type and values, types C data??
<stddef.h> Standard type definitions, C data types??
<stdint.h> Integer types, types, C data?? <stdio.h> StandardBuffered Input/output, the C file Input/output??
<stdlib.h> Standard Library definitions, C Standard library??
<string.h> several string Operations, C string handling?? <strings.h> case-insensitive string Comparisons Issue 4 <stropts.h> Stream manipulation, including IOCTL is Sue 4 <sys/ipc.h> inter-process communication (IPC) Issue 2 <sys/mman.h> Memory management, including POS IX shared memory and memory mapped files Issue 4 <sys/msg.h> POSIX message queues Issue 2 &LT;SYS/RESOURCE.H&G    T Resource usage, priorities, and limiting Issue 4 <sys/select.h> synchronous I/O multiplexing Issue 6 <sys/ Sem.h> XSI (sysv style) semaphores Issue 2 <sys/shm.h> XSI (SYSV style) shared memory Issue 2 &LT;SYS/SOCKET.H&G  T  Main Berkley Sockets Header Issue 6 <sys/stat.h> File information (Stat et al.) Issue 1 <sys/statvfs.h> File System information Issue 4 <sys/time.h> TimE and date functions and structures Issue 4 <sys/times.h> File access and modification times Issue 1 <sys/typ  Es.h> various data types used elsewhere Issue 1 <sys/uio.h> vectored I/O operations Issue 4 <sys/un.h> Unix domain sockets Issue 6 <sys/utsname.h> operating system information, including uname Issue 1 <sys/wait.h&    Gt Status of terminated child processes (= Wait) Issue 3 <syslog.h> System error logging Issue 4 <tar.h> Ma GIC numbers for the TAR archive format Issue 3 <termios.h> allows terminal I/O interfaces Issue 3 &LT;TGMATH.H&G  T
Type-generic Macros, C mathematical functions??
<time.h> type-generic Macros, C date and time functions?? <trace.h> tracing of runtime behavior (deprecated) Issue 6 <ulimit.h> Resource limiting (deprecated in F Avor of <sys/resource.h>) Issue 1 <unistd.h> various essential POSIX functions and constants Issue 1 <utim E.h&gT   Inode access and modification times Issue 3 <utmpx.h> User Accounting database functions Issue 4 <wchar.h>
Wide-character handling, C string handling??
<wctype.h> wide-character Classification and Mapping Utilities, C Character classification??
 <wordexp.h> word-expansion like the shell would perform