strstr

strstr, strcasestr - locate a substring

#include <string.h>
 I char *strstr(const char * haystack , const char * needle );
 #define _GNU_SOURCE
 #include <string.h>
 I char *strcasestr(const char * haystack , const char * needle );

The R strstr () function finds the first occurrence of the substring needle in the string haystack. The terminating '\0' characters are not compared. The R strcasestr () function is like strstr(3), but ignores the case of both arguments.

These functions return a pointer to the beginning of the substring, or NULL if the substring is not found.

The R strstr () function conforms to C89 and C99. The R strcasestr () function is a non-standard extension.

Early versions of Linux libc (like 4.5.26) would not allow an empty needle argument for R strstr (). Later versions (like 4.6.27) work correctly, and return haystack when needle is empty.

index(3), memchr(3), rindex(3), strchr(3), strcasecmp(3), strpbrk(3), strsep(3), strspn(3), strtok(3), wcsstr(3), feature_test_macros(7)