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STRSTR(3) Library Functions Manual STRSTR(3)

strstr, strcasestr, strnstrlocate a substring in a string

library “libc”

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

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

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

The () 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);

memchr(3), memmem(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strtok(3), wcsstr(3)

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

October 11, 2001 FreeBSD-12.0