Thread: char pointer with for loops

Hi, I need help with this please.
I am trying to get the function to determine if the second string entered by the user is contained in the first string by defining the substr() function. I was able to achieve it with a while loop and a nested if statement. I was wondering if someone could help me figure out how to do it with a nested for loop. The prototype is given below and i am using eclipse. Thanks!

Code:

#include <stdio.h>
#include <string.h>
// returns the starting index of the first such occurrence
// where sub_str was found within str - if one exists
// otherwise returns -1
int substr(const char str[], const char sub_str[]);
int main()
{
	char str[255];
	printf("Enter a string: "); fflush(stdout);
	scanf("%s", str);
	char sub_str[255];
	do
	{
		printf("Enter a string to search for (\"quit\" to quit): "); fflush(stdout);
		scanf("%s", sub_str);
		if ( strcmp(sub_str, "quit") )
		{
			int ind = substr(str, sub_str);
			if ( ind == -1 )
			{
				printf("Not found: %s\n", sub_str);
			}
			else
			{
				printf("\"%s\" found at starting index %d\n", sub_str, ind);
			}
		}
	} while ( strcmp(sub_str, "quit") );
	printf("Done!\n");
	return 0;
}