Ex_2.5_any.c

/**
 * Exercise 2.5
 *
 * Write the function any(s1,s2) which 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. ( The standard library function strpbrk does
 * the same job but retuns a pointer to the location
 *
 **/

#include<stdio.h>
#define MAXLINE 1000

int mgetline(char line[],int maxline);
int any(char s1[],char s2[]);

int main(void)
{
	char s1[MAXLINE],s2[MAXLINE];
	int val;
	
	/* Give the first string s1 */
	
	mgetline(s1,MAXLINE);
	
	/* Give the second string s2 */

	mgetline(s2,MAXLINE);

	val = any(s1,s2);

	printf("%d",val);

	return 0;
}

int mgetline(char s[],int lim)
{
	int i,c;
	for(i=0;i<lim-1 && (c=getchar())!=EOF && c!='\n';++i)
		s[i]=c;

	if(c=='\n')
		s[i++]=c;
	s[i]='\0';
}


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

	for(i=0;s1[i]!='\0';++i) 
	{
		// iterate through s2 while trying to find matching character from s1
		for(j=0;(s1[i]!=s2[j]) && s2[j]!='\0';++j) 
			; // continue

		if(s2[j]!='\0' && s2[j] != '\n') { // check that s2 [j]! = '\n', since s1 and s2 both have the character '\n' in the penultimate position of the string.
			return i;
		}
	}

	return -1;
}