memchr(3) Library Functions Manual memchr(3)

memchr, memrchr, rawmemchr - scan memory for a character

Standard C library (libc, -lc)

#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

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.

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.

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

Interface Attribute Value
memchr (), memrchr (), rawmemchr () Thread safety MT-Safe

C11, POSIX.1-2008.
GNU.

POSIX.1-2001, C89, SVr4, 4.3BSD.
glibc 2.2.
glibc 2.1.

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

2024-05-02 Linux man-pages 6.9