malloc and free

malloc and free

[Ankit Jain]

hi

routine xyz uses malloc and free functions. it gives
accurate and correct result if called once. 

but if the function is called in a loop N number of
times then probably it gives segmentation fault.

what is the reason?  can any body guess or test code
is needed?

thanks

ankit jain

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Re: malloc and free

[Ken Foskey]

On Fri, 2004-12-24 at 18:40 +0000, Ankit Jain wrote:
> hi
> 
> routine xyz uses malloc and free functions. it gives
> accurate and correct result if called once. 
> 
> but if the function is called in a loop N number of
> times then probably it gives segmentation fault.
> 
> what is the reason?  can any body guess or test code
> is needed?

If you are using Linux X86 try the code under valgrind.

You could also compile your code with -g and run it under gdb.

Otherwise your question is so vague it is impossible to work out how to
help you.

-- 
Ken Foskey
OpenOffice.org developer

Re: malloc and free

[Sriharsha]

What Irtaylor said is true:
Consider code such as this....

...
...
while(some_condition)
{
    if(some_other_condition)
    {
        ...
        some_var = malloc(some_amount);
        ...
    }
    ...
    free(some_var);
}
...
...

Here, may be for the first time "some_other_condition" may be true, but 
subsequently, it may be false due to which the free (or any code that 
refers to some_var) fails.


lrtaylor@micron.com wrote:

>It's probably a bug in your routine.  However, without seeing your code,
>it's hard to give any good answers.  Step through it with a debugger and
>make sure that you're not trying to free the same memory more than once,
>or access memory that hasn't been allocated yet.
>
>Good luck,
>Lyle 
>
>-----Original Message-----
>From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
>Behalf Of Ankit Jain
>Sent: Friday, December 24, 2004 11:41 AM
>To: gcc
>Subject: malloc and free
>
>hi
>
>routine xyz uses malloc and free functions. it gives
>accurate and correct result if called once. 
>
>but if the function is called in a loop N number of
>times then probably it gives segmentation fault.
>
>what is the reason?  can any body guess or test code
>is needed?
>
>thanks
>
>ankit jain
>
>________________________________________________________________________
>Yahoo! Messenger - Communicate instantly..."Ping" 
>your friends today! Download Messenger Now 
>http://uk.messenger.yahoo.com/download/index.html
>
>
>
>
>  
>

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RE: malloc and free

[lrtaylor]

It's probably a bug in your routine.  However, without seeing your code,
it's hard to give any good answers.  Step through it with a debugger and
make sure that you're not trying to free the same memory more than once,
or access memory that hasn't been allocated yet.

Good luck,
Lyle 

-----Original Message-----
From: gcc-help-owner@gcc.gnu.org [mailto:gcc-help-owner@gcc.gnu.org] On
Behalf Of Ankit Jain
Sent: Friday, December 24, 2004 11:41 AM
To: gcc
Subject: malloc and free

hi

routine xyz uses malloc and free functions. it gives
accurate and correct result if called once. 

but if the function is called in a loop N number of
times then probably it gives segmentation fault.

what is the reason?  can any body guess or test code
is needed?

thanks

ankit jain

________________________________________________________________________
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your friends today! Download Messenger Now 
http://uk.messenger.yahoo.com/download/index.html