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memchr(3) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON 

memchr(3)                Library Functions Manual               memchr(3)

NAME         top

       memchr, memrchr - scan memory for a character

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <string.h>

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

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

       memrchr():
           _GNU_SOURCE

DESCRIPTION         top

       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.

RETURN VALUE         top

       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.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ฌโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ฌโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
       โ”‚ Interface                            โ”‚ Attribute     โ”‚ Value   โ”‚
       โ”œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ผโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ผโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ค
       โ”‚ memchr(), memrchr()                  โ”‚ Thread safety โ”‚ MT-Safe โ”‚
       โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ดโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ดโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜

STANDARDS         top

       memchr()
              C11, POSIX.1-2008.

       memrchr()
              GNU.

HISTORY         top

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

       memrchr()
              glibc 2.2.

SEE ALSO         top

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

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
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Linux man-pages 6.18            2026-02-25                      memchr(3)

Pages that refer to this page: bstring(3),  ffs(3),  rawmemchr(3),  strchr(3),  strpbrk(3),  strsep(3),  strspn(3),  strstr(3),  strtok(3),  wmemchr(3),  signal-safety(7)

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