MEMCHR(3) Linux Programmer's Manual MEMCHR(3)
memchr, memrchr, rawmemchr - scan memory for a character
void *memchr(const void *s, int c, size_t n);
void *memrchr(const void *s, int c, size_t n);
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 inter-
preted 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(): it assumes (i.e., the programmer knows
for certain) that an instance of c lies somewhere in the memory area starting at the loca-
tion pointed to by s, and so performs an optimized search for c (i.e., no use of a count
argument to limit the range of the search). If an instance of c is not found, the results
are unpredictable. The following call is a fast means of locating a string's terminating
char *p = rawmemchr(s, '\0');
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, if one is found. If no
matching byte is found, the result is unspecified.
rawmemchr() first appeared in glibc in version 2.1.
memrchr() first appeared in glibc in version 2.2.
The memchr() function conforms to SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
The memrchr() function is a GNU extension, available since glibc 2.1.91.
The rawmemchr() function is a GNU extension, available since glibc 2.1.
ffs(3), index(3), rindex(3), strchr(3), strpbrk(3), strrchr(3), strsep(3), strspn(3),
This page is part of release 3.53 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at