STRSTR(3)                BSD Library Functions Manual                STRSTR(3)

NAME
     strstr, strcasestr, strnstr -- locate a substring in a string

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #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);

DESCRIPTION
     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-termi-
     nated string needle in the string haystack, where not more than len char-
     acters 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);

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

STANDARDS
     The strstr() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

BSD                            October 11, 2001                            BSD