subject
Write the function any(s1, s2) to return the first occurrence of any character in the string S2 as a result. If s 1 does not contain the characters in s2, then - 1 is returned. (The standard library function strpbrk has the same function, but it returns a pointer to that location.)

Title Analysis
If you don't understand how any character works, mark the position of each character in string 1. The implementation method is similar to 2-4.

Programming implementation

#include <stdio.h>
#define MAXLINE 1000

int positionc(char s1[], char s2[], int p[]);

int main()
{
    int i, positions[MAXLINE];
    char c, sfirst[MAXLINE], ssecond[MAXLINE];

    i = 0;
    printf("Please input string1:");
    while ((c = getchar()) != '\n')
        sfirst[i++] = c;
    sfirst[i] = '\0';

    i = 0;
    printf("Please input string2:");
    while ((c = getchar()) != '\n')
        ssecond[i++] = c;
    ssecond[i] = '\0';

    positionc(sfirst, ssecond, positions);
    i = 0;
    while (ssecond[i] != '\0')
    {
        printf("%c\t%d\n",ssecond[i], positions[i]);
        i++;
    }
}

int positionc(char s1[], char s2[], int p[])
{
    int m, n, l, r;

    n = 0;
    while (s2[n] != '\0')
        {
            p[n] = 0;
            m = l = 0;
            while (s1[m] != '\0')
                {
                    if (s1[m] != s2[n] && s1[m+1] != '\0')
                        l++;
                    else if ( s1[m] == s2[n])
                        {
                            p[n] = l;
                            break;
                        }
                    else if (s1[m] != s2[n] && s1[m + 1] == '\0')
                        {
                            p[n] = -1;
                            break;
                        }
                    m++;
                }
            if (s1[m] == '\0' && l == 0)
                        p[n] = -1;
            n++;
        }
}