PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       string.h — string operations

SYNOPSIS

       #include <string.h>

DESCRIPTION

       Some of the functionality described on this reference page extends the ISO C standard. Applications shall
       define the appropriate feature test macro (see the System Interfaces volume of POSIX.1‐2017, Section 2.2,
       The Compilation Environment) to enable the visibility of these symbols in this header.

       The <string.h> header shall define NULL and size_t as described in <stddef.h>.

       The <string.h> header shall define the locale_t type as described in <locale.h>.

       The following shall be declared as functions and may also be defined as macros. Function prototypes shall
       be provided for use with ISO C standard compilers.

           void    *memccpy(void *restrict, const void *restrict, int, size_t);
           void    *memchr(const void *, int, size_t);
           int      memcmp(const void *, const void *, size_t);
           void    *memcpy(void *restrict, const void *restrict, size_t);
           void    *memmove(void *, const void *, size_t);
           void    *memset(void *, int, size_t);
           char    *stpcpy(char *restrict, const char *restrict);
           char    *stpncpy(char *restrict, const char *restrict, size_t);
           char    *strcat(char *restrict, const char *restrict);
           char    *strchr(const char *, int);
           int      strcmp(const char *, const char *);
           int      strcoll(const char *, const char *);
           int      strcoll_l(const char *, const char *, locale_t);
           char    *strcpy(char *restrict, const char *restrict);
           size_t   strcspn(const char *, const char *);
           char    *strdup(const char *);
           char    *strerror(int);
           char    *strerror_l(int, locale_t);
           int      strerror_r(int, char *, size_t);
           size_t   strlen(const char *);
           char    *strncat(char *restrict, const char *restrict, size_t);
           int      strncmp(const char *, const char *, size_t);
           char    *strncpy(char *restrict, const char *restrict, size_t);
           char    *strndup(const char *, size_t);
           size_t   strnlen(const char *, size_t);
           char    *strpbrk(const char *, const char *);
           char    *strrchr(const char *, int);
           char    *strsignal(int);
           size_t   strspn(const char *, const char *);
           char    *strstr(const char *, const char *);
           char    *strtok(char *restrict, const char *restrict);
           char    *strtok_r(char *restrict, const char *restrict, char **restrict);
           size_t   strxfrm(char *restrict, const char *restrict, size_t);
           size_t   strxfrm_l(char *restrict, const char *restrict,
                        size_t, locale_t);

       Inclusion of the <string.h> header may also make visible all symbols from <stddef.h>.

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <locale.h>, <stddef.h>, <sys_types.h>

       The System Interfaces volume of POSIX.1‐2017, Section 2.2, The Compilation Environment, memccpy(),
       memchr(), memcmp(), memcpy(), memmove(), memset(), strcat(), strchr(), strcmp(), strcoll(), strcpy(),
       strcspn(), strdup(), strerror(), strlen(), strncat(), strncmp(), strncpy(), strpbrk(), strrchr(),
       strsignal(), strspn(), strstr(), strtok(), strxfrm()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .