A friend sent me a snippet I don't understand. How does this work?

Question

I spent some time trying to understand what was going on with this code but in the end I couldn't fully figure it out.

void knock_knock(char *s){
 while (*s++ != '\0')
  printf("Bazinga\n");
}

int main() {
 int data[5] = { -1, -3, 256, -4, 0 };
 knock_knock((char *) data);
 return 0;
}

I was surprised when I saw it didn't print 'Bazinga' 5 times, but 8. My next thought was that it was just iterating over the length of the pointer, so it would make sense that it printed 8 times. But, then I changed the first number of the array from -1, to check whether the data truly was relevant or not, and this is where I was confused. It didn't print 8 times anymore, but just once. Why?

Answer 1

Using the following code

#include<stdio.h>

void knock_knock(char *s)
{
    while (*s++ != '\0')
        printf("Bazinga\n");
}

int main()
{
    int data[5] = { -1, -3, 256, -4, 0 };
    printf("%08X - %08X - %08X\n", data[0], data[1], data[2]);
    knock_knock((char *) data);
    return 0;
}

You can see that HEX values of data array are

FFFFFFFF - FFFFFFFD - 00000100

Function knock_knock print Bazinga until the pointed value is 0x00 due to

while (*s++ != '\0')

But the pointer here is pointing chars, so is pointing a single byte each loop and so, the first 0x00 is reached accessing the "first" byte of third value of array.