Question

#include <stdio.h>
#define MAX 1000
void any(char s1[], char s2[], char s3[]);
int main()
{
    char string1[MAX], string2[MAX], string3[MAX];
    printf("Jepni stringen 1\n");
    scanf("%s", &string1);  //saving string 1
    printf("Jepni stringen 2\n");
    scanf("%s", &string2);  //saving string 2
    any(string1, string2, string3); /*comparing characters from string 2 to string 1    and saving the places where they are equal on third string */
    printf("%d", string3[0]);   //printing the first character of the third string
    return 0;
}

void any(char s1[], char s2[], char s3[])
{
    int i, j, k;
    k = 0;
    for (j = 0; j != '\0'; j++) {
        for (i = 0; i != '\0'; i++) {
            if (s1[i] == s2[j]) {
            s3[k] = i;
            j++;
            k++;
            }
        }
    }
}

I am trying to create a c program that scans 2 strings (saves them on string 1 and 2) than the program using function any will see character by character if the string 2 characters are equal with the string 1,If they are it will give the first position where they are found.In case nothing is found it displays a -1.The program asks for the first character that is equal,thats why i am printing always the first character from string 3.The program isnt working cuz it always prints -1.
Example if i put on string 1 dad
and on string 2 the character d
dhe program should display the 0 position
if i put dad on string 1
and on string 2 i put a
it should display 1.

Answer 1

First of all the for loop doesn’t begin because the condition is that j shall be different from zero.In ASCII ‘\0’ is zero (maybe not on all machines), so you rather want to check that s2[j] is different from zero.Same for i.
Another thing is that s3 is an array of chars, so putting s3[k]=i doesn’t make it equal to ‘1’ or ‘2’, but to 1 or 2 (ASCII values), so you should add 48 to i (good till ‘9’, then you’ll have two digits), or print the string character per character, with the %d format specifier:

void any(char s1[], char s2[], char s3[])
{
    int i, j, k;
    k = 0;
    for (j = 0; s2[j] != '\0'; j++) {
        for (i = 0; s1[i] != '\0'; i++) {
            if (s1[i] == s2[j]) {
                s3[k] = i;
                j++;
                k++;
            }
        }
    }
}

Maybe I’m missing some other error, try the code and run it to see if it’s right (also remember to use the %d specifier to print s3).