STRSTR(3) Linux Programmer's Manual STRSTR(3) NAME strstr - locate a substring SYNOPSIS #include <string.h> char *strstr(const char *haystack, const char *needle); DESCRIPTION The strstr() function finds the first occurrence of the substring needle in the string haystack. The terminating ` ' characters are not compared. RETURN VALUE The strstr() function returns a pointer to the beginning of the substring, or NULL if the substring is not found. BUGS Early versions of Linux libc (like 4.5.26) would not allow an empty argument. Later versions (like 4.6.27) work correctly, and return haystack when needle is empty. CONFORMING TO ISO 9899 SEE ALSO index(3), memchr(3), rindex(3), strchr(3), strpbrk(3), strsep(3), strspn(3), strtok(3) GNU 1993-04-12 STRSTR(3)