why this code works in C

Question

#include <stdio.h>

int main(){

char array[2];
array[0] = 'q';
array[1] = 'a';
printf("%s",array);

return 0;
}

if you ask me this code should not work. printf prints array[2] like string but it's not a string. When i execute it, it works perfectly. Can you explain why?

Answer 1

When i execute it, it works perfectly.

You just got (un)lucky: your code exhibits undefined behavior, because it lets the printf's %s parameter run off the end of the sequence of characters that is not null-terminated.

A string in C is a sequence of char, which must have an extra character with the value 0, called the null terminator. Here is a way to make your code work without undefined behavior:

char array[3];
array[0] = 'q';
array[1] = 'a';
array[2] = '';