Why doesn't this end

#include <stdio.h>

main()
{

    int a;

while(a != 256)
    {putchar(a);
    a++;}
}

But if I add  a = 0;  after int a;, it ends fine?

Something to do with a variable not being initialized properly, and therefore, not being able to be compared or something?

Compiled with Code::Blocks+GCC or mingw or something. The debugger also reports no relevant issues with the initial code.

>>5
>and the program still compiles and runs anyway
Turn on warnings.