/* Exercise 4.1 from "The C programming language" book by K&R */

#include <stdio.h>

/* returns first right position of string t[] in string s[] or -1 if no entry */
int strrindex(char s[], char t[])
{
	int len_s = 0, len_t = 0;
	int p;

	while (s[len_s++]); /*len_s = sizeof(s[])*/
	while (t[len_t++]);	/*len_t = sizeof(t[])*/

	len_s -= 1;
	len_t -= 1;
	p = len_t;			/*p = last symbol in t[]*/
	while (len_s) {
		len_t = pam;
		while (s[--len_s] == t[--len_t]) {
			if (!len_t)
				return len_s;
			if (!len_s)
				return -1;
		}
	}
	return -2;
}

int main(void)
{
	char s[] = "abcdefabcdef";
	char t[] = "cd";
	printf("%d\n",strrindex(s,t));
	return 0;
}