Re: Help me stay away from visual C++ :)

[egm2@jps.net]

On 26 Jul, Moses Leslie wrote:
  |  I'm taking an intro C class, and of course everything there is run on win95. 
  |  For a project we're doing now, I need to be able to tell if a scanf("%d",&x)
  |  actually gets an int or not, but scanf seems to freak out if it gets anything
  |  but an int.  For example:
  |  
  |  int test;
  |  for(;;)
  |  {
  |          printf("Status is %d\n",scanf("%d",&test));
  |          fflush(stdin); 
  |  }
  |  
  |  prints out "Status is 1" if it gets an int, but freaks out and keeps printing
  |  "Status is 0" over and over if you give it a char.  The same snippet works fine
  |  under visual C++.  Is this something that's (most likely) broken in vc++, or
  |  perhaps (less likely) broken in glibc 2.1?  All I have to test it on is a
  |  potato box, so I don't know if other versions of gcc have the same problem.
  |  
  |  Pointers to faqs or relevant docs are appreciated, I've spent an entire day
  |  poking around in various gcc things (I hate info :)) but with no luck.
  |  
  |  Thanks,
  |  Moses
  |  
  |  --
  |  Moses Leslie <marmoset@l8r.net>
  |  
  |  

Firstly, scanf is evil. Don't use it for user input! If you want to see
if input is an integer or not, you need to read it as a string first
with, may I suggest fgets(), or simply getchar() for a single
character.  Then use isdigit() to see if it is a digit.  Also,
fflush(stdin) is guaranteed to give "undefined behavior", which is
certainly part of your problem. I highly recommend comp.lang.c as a
place to get expert advice on ANSI/ISO C (don't ask about OS specific
stuff! and please read the C FAQ).
-- 

Eric G. Miller
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