strstr, strcasestr — locate a substring
#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) ; |
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(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 strstr
() function
conforms to C89 and C99. The strcasestr
() function is a non-standard
extension.
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.
index(3), memchr(3), rindex(3), strchr(3), strcasecmp(3), strpbrk(3), strsep(3), strspn(3), strtok(3), wcsstr(3), feature_test_macros(7)
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