NAME¶

strstr, strcasestr - locate a substring

SYNOPSIS¶

#include <string.h>

char *strstr(const char *haystack, const char *needle);

#define _GNU_SOURCE

#include <string.h>

char *strcasestr(const char *haystack, const char *needle);

DESCRIPTION¶

The strstr() function finds the first occurrence of the substring needle in the string haystack. The terminating '\0' characters are not compared.

The strcasestr() function is like strstr(), but ignores the case of both arguments.

RETURN VALUE¶

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

CONFORMING TO¶

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

BUGS¶

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

SEE ALSO¶

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

COLOPHON¶

This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.