Persistent failure of 'break' statement ( novice )

[pdlemper at earthlink.net]

Thanks Mark & Rhodri.  Neither works.

I'm using Notepad2 as editor.  Don't use the tab. Each space
counted with spacebar & recounted.  Rewrote the block from
scratch as new script and eliminated the print line in the loop.
Now no error message, but it will go on forever despite repeatedly
entering 0.  Have to get out with ctrl-c .     

while True :
    num = int(input())
    if num == 0 :
        break

print('done')

           Frusting: I'm missing something fundamental. Dave WB3DWE