Path: utzoo!attcan!uunet!husc6!mailrus!uflorida!novavax!hcx1!hcx2!danr
From: danr@hcx2.SSD.HARRIS.COM
Newsgroups: comp.lang.c
Subject: Re: Re^2: QuickC
Message-ID: <44100010@hcx2>
Date: 6 Sep 88 22:39:00 GMT
References: <140@ambone.UUCP>
Lines: 41
Nf-ID: #R:ambone.UUCP:140:hcx2:44100010:000:1391
Nf-From: hcx2.SSD.HARRIS.COM!danr    Sep  6 18:39:00 1988


/* Written 11:45 am  Aug 27, 1988 by leif@ambone.UUCP in hcx2:comp.lang.c */
/* ---------- "Re^2: QuickC" ---------- */
TURGUT@TREARN.BITNET (Turgut Kalfaoglu) writes:
>square(num)
>int num;
>{
>  num = num*num;
>}

>OK? There is no 'return' statement in the function. However, it works!
>I get '4' as an answer. So I thought maybe it was keeping the result
>of the last operation, so I added some dummy lines,

>square(num)
>int num;
>{
>  int dummy;
>  num = num*num;
>  dummy=222;
>}

>but the call STILL works... Can anyone shed some light onto this?
>WHY does it work?

My answer has not been tested but I'm quite sure that this is the
right answer to your question:

When you call a function i C the parameters is put on the stack. You
function uses the stack to keep the variable num and when the function
return the result is popped from the stack - which (unfortunately(!)
is the temporary variable num! 

   Leif Andrew Rump, Ambrasoft A/S, Roejelskaer 15, DK-2840 Holte (Denmark)
 UUCP: leif@ambone.dk, phone: +45 2424 111; ABC BBS: +45 68 00 544 (2:505/38)

Please note the node-change:                    Ambone, Italian for a pulpit
(The following interpretations emerged          Am_bone, Ambrasoft A/S bone
 when Ambone was put down on paper and          Amb_one, Ambrasoft A/S #one
 accepted - they are solely mine!!!!!)          ...
/* End of text from hcx2:comp.lang.c */