write the function any(s1,s2) code example

Example: write the function any(s1,s2)

/**
 * 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,check_next_char;

    check_next_char=1;

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

        if(s2[j]=='\0') {
            check_next_char=1;
            i++; // go for the next char in s1
        }
        else
            check_next_char=0; // match found
    }

    if(s1[i]=='\0')
        return -1;
    else
        return i;
}