Re: loop bug using mingw3.2 and cygwin in M$ Windows

[James E Wilson <wilson at specifixinc dot com>]

Gerald Lafreniere wrote:
> Running this code you will produce the bug if you input anything other
> than 1 2 3 or 4

The problem here is that you are reading from stdin which is line 
buffered, so getchar does not return until the user hits return.  return 
however is a character too, so if the user typed "5<RET>" then we have 
two characters, and we end up looping twice.

This is easier to see if you type something like "5 6 7<RET>" in which 
case we loop 6 times before waiting for another character.

Try checking the user input to verify that the user only typed one 
character, and also add code to ignore the end-of-line character.

You could also try turning off the line buffering so getchar() returns 
after one character, but this is more complicated, and may be OS 
dependent.  See setvbuf, setbuf, setbuffer.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com