strstr3
Locate a substring in a string
Usage
#include <string.h>
char *
strstr(const char *haystack, const char *needle);
char *
strcasestr(const char *haystack, const char *needle);
char *
strnstr(const char *haystack, const char *needle, size_t len);
#include <string.h>
#include <xlocale.h>
char *
strcasestr_l(const char *haystack, const char *needle, locale_t loc);
Library
Standard C Library (libc, -lc)
Overview
The strstr() function locates the first occurrence of the null-terminated string needle in the null-terminated string haystack.
The strcasestr() function is similar to strstr(), but ignores the case of both strings.
The strnstr() function locates the first occurrence of the null-terminated string needle in the string haystack, where not more than len characters are searched. Characters that appear after a ‘\0’ character are not searched. Since the strnstr() function is a FreeBSD specific API, it should only be used when portability is not a concern.
While the strcasestr() function uses the current locale, the strcasestr_l() function may be passed a locale directly. See xlocale(3) for more information.
Return values
If needle is an empty string, haystack is returned; if needle occurs nowhere in haystack, NULL is returned; otherwise a pointer to the first character of the first occurrence of needle is returned.
Examples
The following sets the pointer ptr to the "Bar Baz" portion of largestring:
const char *largestring = "Foo Bar Baz"; const char *smallstring = "Bar"; char *ptr; ptr = strstr(largestring, smallstring);
The following sets the pointer ptr to NULL, because only the first 4 characters of largestring are searched:
const char *largestring = "Foo Bar Baz"; const char *smallstring = "Bar"; char *ptr; ptr = strnstr(largestring, smallstring, 4);
Releases
163 releases since Mac OS X 10.0; the text changed 6 times.