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From: brianh@hpcvia.CV.HP.COM (brian_helterline)
Newsgroups: comp.lang.c
Subject: Re: Novice MicroSoft C5.1 question
Message-ID: <31530011@hpcvia.CV.HP.COM>
Date: 26 Jul 90 15:32:20 GMT
References: <9609@tekigm2.MEN.TEK.COM>
Organization: Hewlett-Packard Co., Corvallis, Oregon
Lines: 51


>  Could anyone explain the unexpected output of these two programs
>to me please??  Being a beginning C person, it's entirely likely that
>I have a simple syntax error or my concept of pointers is wrong.  I
>am using MicroSoft C5.1 on a '386@16MHz.  I posted this once before,
>but received no help; not even to tell me how stupid I am and that
>such a simple question is beneath response.    As to the question:

>Running this:

[ example deleted ]

>#include <stdio.h>
>main()
>{
> int x=100;
> int *y;
> y= &x;
> printf("\nx:%d  &x:%u",x,&x);
> printf("  y(add of x):%u  &y(add of y):%u  *y(value of x):%d\n",y,&y,*y);
>}
>
>Produces the unexpected output:
>x:100  &x:11094  y(add of x):11094  &y(add of y):7647  *y(value of x):11090

>I do not understand why there is a difference.  Could some nice soul explain
>this in a way a novice could understand??  Thanks in advance.
>----------

	The problem is that you are printing out an address using %u
	which expects sizeof( unsigned int ) bytes on the stack but
	you are shoving an address onto the stack.  To print out an
	address, use %p ( MSC RunTime Ref pg 459 ).  Also, it is
	important to know what memory model you are using.  The %p
	requires a far pointer.  The code below will work with any
	memory model.  (I did not test this code :)

#include <stdio.h>
main()
{
 int x=100;
 int *y;
 y= &x;
 printf("\nx:%d  &x:%p",x,(int far *)&x);
 printf("  y(add of x):%p  &y(add of y):%p  *y(value of x):%d\n",(int far *)y,
			(int far *)&y, *y);
}


Hope this helps.
-Brian