#include <string.h> 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)):
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 location 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 null byte:
char *p = rawmemchr(s, '\0');
|memchr(), memrchr(), rawmemchr()||Thread safety||MT-Safe|
The memrchr() function is a GNU extension, available since glibc 2.1.91.