Manual Pages  — STRSTR

strstr – locate a substring in a string

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES EXAMPLES SEE ALSO STANDARDS HISTORY

Standard C Library (libc, -lc)

#include <string.h>

char *
strstr(const char *big, const char *little);

char *
strcasestr(const char *big, const char *little);

char *
strnstr(const char *big, const char *little, size_t len);

#include <string.h>

#include <xlocale.h>

char *
strcasestr_l(const char *big, const char *little, locale_t loc);

The strstr() function locates the first occurrence of the null-terminated string little in the null-terminated string big.

The strcasestr() function is similar to strstr(), but ignores the case of both strings.

The strcasestr_l() function does the same as strcasestr() but takes an explicit locale rather than using the current locale.

The strnstr() function locates the first occurrence of the null-terminated string little in the string big, 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.

If little is an empty string, big is returned; if little occurs nowhere in big, NULL is returned; otherwise a pointer to the first character of the first occurrence of little is returned.

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);

The strstr() function conforms to ISO/IEC 9899:1990 ("ISO C90").

The strnstr() function was introduced by FreeBSD 4.5 and is non-standard.