memchr(3)                  Library Functions Manual                  memchr(3)

NAME
       memchr, memrchr, rawmemchr - scan memory for a character

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <string.h>

       void *memchr(const void s[.n], int c, size_t n);
       void *memrchr(const void s[.n], int c, size_t n);

       [[deprecated]] void *rawmemchr(const void *s, int c);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       memrchr(), rawmemchr():
           _GNU_SOURCE

DESCRIPTION
       The memchr() function scans the initial n bytes of the memory area
       pointed to by s for the first instance of c.  Both c and the bytes of
       the memory area pointed to by s are interpreted as unsigned char.

       The memrchr() function is like the memchr() function, except that it
       searches backward from the end of the n bytes pointed to by s instead
       of forward from the beginning.

       The rawmemchr() function is similar to memchr(), but it assumes (i.e.,
       the programmer knows for certain) that an instance of c lies somewhere
       in the memory area starting at the location pointed to by s.  If an
       instance of c is not found, the behavior is undefined.  Use either
       strlen(3) or memchr(3) instead.

RETURN VALUE
       The memchr() and memrchr() functions return a pointer to the matching
       byte or NULL if the character does not occur in the given memory area.

       The rawmemchr() function returns a pointer to the matching byte.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |memchr (), memrchr (), rawmemchr ()         | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       memchr()
              C11, POSIX.1-2008.

       memrchr()
       rawmemchr()
              GNU.

HISTORY
       memchr()
              POSIX.1-2001, C89, SVr4, 4.3BSD.

       memrchr()
              glibc 2.2.

       rawmemchr()
              glibc 2.1.

SEE ALSO
       bstring(3), ffs(3), memmem(3), strchr(3), strpbrk(3), strrchr(3),
       strsep(3), strspn(3), strstr(3), wmemchr(3)

Linux man-pages 6.7               2023-10-31                         memchr(3)