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.

It should end, you just haven't ran it long enough. If you actually remove the putchar call, it should end reasonably fast, depending on the speed of your CPU.