/*
 * Simple program demonstrating use of string function and pointer
 * arithmetic.
 */
#include <stdio.h>
#include <string.h>

/*
 * look for needle in haystack and print index if found
 */
void foobar(char * haystack, char * needle) {
	char * p = strstr(haystack, needle);
	if (p == NULL) {
		printf("in '%s' did not find '%s'\n", haystack, needle);
	}
	else {
		/* 
		 * p points to start of "needle" in "haystack" if found,
		 * so the following line finds its index
		 */
		int index = p - haystack;
		printf("in '%s' found '%s' at %d\n", haystack, needle, index);
	}
}

int main(void) {
	foobar("well hello there world", "hello");
	foobar("hello", "hello");
	foobar("goodbye all", "hello");
	return 0;
}