Re: What am I doint wrong here?!?!

[Chris Croswhite <ccroswhite at get2chip dot com>]

Ignore my previous message.....

Source coude listed below, -g runs fine, -O2 core dumps, why (with
incorrect code) does this work for -g and not for -O?

TIA,
Chris
On Sun, 2003-02-23 at 14:55, Oscar Fuentes wrote:
> Chris Croswhite <ccroswhite at get2chip dot com> writes:
> 
> > ummm... I tried it with the int/&int and it works for -O2, however,
> > when using the other way, I have compiled this with -g and no
> > problems, as soon as I use -O(1,2,3) I run into the core dump, why
> > do I get a core dumb than and not with -g?
> 
> Could you post the source code that produces the core dumb? 
> 
> [No need to email me. Post the the list.]
>  
> > On Sun, 2003-02-23 at 13:56, Oscar Fuentes wrote:
> > > Chris Croswhite <ccroswhite at get2chip dot com> writes:
> > > 
> > > > gcc 3.2.2 on x86 (686):
> > > > What am I doing wrong here:
> > > > 
> > > > #include <math.h>
> > > > #include <stdio.h>
> > > > 
> > > > int main () {
> > > >   double val, num;
> > > >   int *exp;
> > > > 
> > > >   val = 5.0/2.0;
> > > > 
> > > >   num = frexp(val, exp);
> > > > 
> > > >   printf("num is %g\n", val);
> > > > 
> > > > return 1;
> > > > }
> > > > 
> > > > gcc -static -O2 foo.c -o foo
> > > > 
> > > > foo generates a dump.
> > > 
> > > You provided a pointer, but it points nowhere. 'frexp' uses that
> > > pointer to store a value on the address it points to. Either you use
> > > 
> > >    /* We allocate a piece of memory and set 'exp' to point there */
> > >    int *exp = (int*) malloc( sizeof(int) );
> > >  
> > >    val = 5.0/2.0;
> > >  
> > >    num = frexp(val, exp);
> > > 
> > > or simply
> > > 
> > >    /* Use a plain variable */
> > >    int exp;
> > >  
> > >    val = 5.0/2.0;
> > > 
> > >    /* We pass the address of 'exp' */ 
> > >    num = frexp(val, &exp);
> > > 
> > > HTH
> > -- 
> > Chris Croswhite <ccroswhite at get2chip dot com>
> > Get2Chip, Inc.
> > 
> > 
-- 
Chris Croswhite <ccroswhite at get2chip dot com>
Get2Chip, Inc.