/* Returns the first location in the string s1 where any character
 * from the string s2 occurs, or -1 if s1 contains no characters from
 * s2.
 */

#define MAXLEN 50 /* maximum allowable input */

#include <stdio.h>

void getstring(char input[]);
char any(char s1[], char s2[]);

int main() {
     char s1[MAXLEN], s2[MAXLEN];
     int foo;

     getstring(s1);
     getstring(s2);

     if ((foo = any(s1, s2)) != -1) {
	  printf("The first character in s1 which also occurs in s2 is\n");
	  printf("%c, character number %d (zero based).\n", s1[foo], foo);
     } else
	  printf("No matches between the two strings.\n");

     return 0;
}

void getstring(char input[]) {
     char i, c;

     printf("Please enter a string: ");
     i = 0;
     while ((c = getchar()) != '\n') {
	  if (c == EOF) {
	       printf("Oh, I see! Running away, eh?\n");
	       exit(0);
	  } else if (i == MAXLEN) {
	       printf("Ow, OW, OUCH! IT'S TOO BIG FOR ME!\n");
	       exit(0);
	  } else
	       input[i++] = c;
     }
     input[i] = '\0';
}

char any(char s1[], char s2[]) {
     int i, j;

     for (i = 0; s1[i] != '\0'; i++) {
	  for (j = 0; s2[j] != '\0'; j++) {
	       if (s1[i] == s2[j])
		    return i;
	  }
     }

     return -1;
}