strnstr.c File Reference

#include <string.h>

Include dependency graph for strnstr.c:

Go to the source code of this file.

Functions
char *	strnstr (const char *s, const char *find, size_t slen)
	Finds the first occurrence of find in the initial slen characters of the object pointed to by s. More...

Function Documentation

strnstr()

char* strnstr	(	const char *	s,
		const char *	find,
		size_t	slen
	)

Finds the first occurrence of find in the initial slen characters of the object pointed to by s.

Locates the first occurrence of the null-terminated string find in the string s, where not more than slen characters are searched. Characters that appear after a ‘\0’ character are not searched.

The behavior is undefined if either find or s is not a pointer to a null-terminated byte string.

Parameters

s	pointer to the null-terminated byte string to examine
find	pointer to the null-terminated byte string to search for
slen	maxinum number of characters to search for

Returns

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

Definition at line 48 of file strnstr.c.

{
    char c;

    if((c = *find++) != '\0')
    {
        size_t len = strlen(find);
        do
        {
            char sc;
            do
            {
                if(slen-- < 1 || (sc = *s++) == '\0')
                {
                    {
                        return (NULL);
                    }
                }
            } while(sc != c);
            if(len > slen)
            {
                {
                    return (NULL);
                }
            }
        } while(strncmp(s, find, len) != 0);
        s--;
    }
    return ((char*)(uintptr_t)s);
}

References NULL, strlen(), and strncmp().