/* strsearch.c

 *

 * Copyright (c) Chris Putnam 1995-2018

 *

 * Source code released under the GPL version 2

 *

 * strsearch() locates a case-independent substring

 *    e.g. a case-independent version of strstr()

 *

 * returns pointer to first occurrence of substring needle in

 * the string haystack when found, NULL if not found

 *

 * '\0' characters terminating strings are not compared

 *

 * strsearch returns haystack when needle is empty as per strstr()

 * conventions

 *

 */

#include <stdio.h>

#include <ctype.h>

#include "strsearch.h"

char *strsearch (const char *haystack, const char *needle)

{

	char *returnptr=NULL;

	unsigned long pos=0;

	if ( !(*needle) ) returnptr = (char *) haystack;

	while (*(haystack+pos) && returnptr==NULL) {

		if ( toupper((unsigned char)*(haystack+pos)) == toupper((unsigned char)*(needle+pos)) )

			pos++;

		else {

			pos = 0;

			haystack++;

		}

		if ( ! (*(needle+pos)) ) returnptr = (char *) haystack;

	}

	return returnptr;

}