Join strings

#include <stdio.h>
#include <string.h>

int main() {
    char first_string[32];
    char second_string[32];
    scanf("%s", first_string);
    scanf("%s", second_string);

    int i;
    for(i = 0; second_string[i] != '\0'; i++) {
        int first_length = strlen(first_string);
        first_string[first_length] = second_string[i];
        first_string[first_length + 1] = '\0';
    }

    printf("%s\n", first_string);

    return 0;
}