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memchr(3) Library Functions Manual memchr(3)
memchr, memrchr - scan memory for a character
Standard C library (libc, -lc)
#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
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 memchr() and memrchr() functions return a pointer to the
matching byte or NULL if the character does not occur in the given
memory area.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ memchr(), memrchr() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
memchr()
C11, POSIX.1-2008.
memrchr()
GNU.
memchr()
POSIX.1-2001, C89, SVr4, 4.3BSD.
memrchr()
glibc 2.2.
bstring(3), ffs(3), memmem(3), strchr(3), strpbrk(3), strrchr(3),
strsep(3), strspn(3), strstr(3), wmemchr(3)
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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)