Looks for a pattern in string.

find_string_pattern.c

#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

int findPatternRight(char* s, char* pat){
	bool flag = true;
	int i, j, k, left;

	int len_s = strlen(s);
	int len_pat = strlen(pat);

	for(i=len_s-1, left=len_s-len_pat;left>=0;i--, left--){
		flag = true;
		for(j=left, k=0;k<len_pat;j++, k++){
			if(s[j] != pat[k]){
				flag = false;
				break;
			}
		}
		if(flag){
			return left;
		}
	}

	return -1;
}

int main(int argc, char const *argv[])
{
	char *in;
	char *pat;

	in = malloc( 10000000 * sizeof(char));
	pat = malloc( 10000000 * sizeof(char));

	printf("Enter a string to search in:");
	scanf("%s", in);

	printf("Enter a pattern:");
	scanf("%s", pat);

	int ind = findPatternRight(in, pat);

	printf("%d\n", ind);

	return 0;
}