Memory Allocation Problem

Memory Allocation Problem

[Ankit Jain]

      1 #include <stdio.h>
      2 int main()
      3 {
      4    double a[1450][1450];
      5
      6    a[1449][0] = 999;
      7    printf( "%lf\n", a[1449][0] );
      8    return 1;
      9 }


it gives segementation fault

if i use malloc also it gives wrong result

what to do?

ankit

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Re: Memory Allocation Problem

[Sriharsha Vedurmudi]

Ankit Jain wrote:

>      1 #include <stdio.h>
>      2 int main()
>      3 {
>      4    double a[1450][1450];
>      5
>      6    a[1449][0] = 999;
>      7    printf( "%lf\n", a[1449][0] );
>      8    return 1;
>      9 }
>
>
>it gives segementation fault
>  
>
I tried, but it ran well. Except ofcourse, I changed "return 1" to 
"return 0" (you dont want to return an error from Main)

>if i use malloc also it gives wrong result
>
>what to do?
>  
>
I guess your system is lacking the memory required to allocate 1450 * 
1450 * 4 bytes on stack. Try making it static.

-Harsha.

>ankit
>
>________________________________________________________________________
>Yahoo! Messenger - Communicate instantly..."Ping" 
>your friends today! Download Messenger Now 
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>  
>

Re: Memory Allocation Problem

[Ankit Jain]

 --- Sriharsha Vedurmudi
<sriharsha.v@redpinesignals.com> wrote: 
> 
> Ankit Jain wrote:
> 
> >      1 #include <stdio.h>
> >      2 int main()
> >      3 {
> >      4    double a[1450][1450];
> >      5
> >      6    a[1449][0] = 999;
> >      7    printf( "%lf\n", a[1449][0] );
> >      8    return 1;
> >      9 }
> >

well i am sorry its return 0 only

i have 128 mb RAM. it gives segmentation fault while
running

i tried it on 512 MB Ram also it gives segemntation
fault. around 400 MB of Ram was free when i tried to
run that program

thanks 
ankit
> >
> >it gives segementation fault
> >  
> >
> I tried, but it ran well. Except ofcourse, I changed
> "return 1" to 
> "return 0" (you dont want to return an error from
> Main)
> 
> >if i use malloc also it gives wrong result
> >
> >what to do?
> >  
> >
> I guess your system is lacking the memory required
> to allocate 1450 * 
> 1450 * 4 bytes on stack. Try making it static.
> 
> -Harsha.
> 
> >ankit
> >
>
>________________________________________________________________________
> >Yahoo! Messenger - Communicate instantly..."Ping" 
> >your friends today! Download Messenger Now 
> >http://uk.messenger.yahoo.com/download/index.html
> >  
> >
>  

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RE: Memory Allocation Problem

[Chandan Chopra]

[-- Attachment #1: Type: text/plain, Size: 2137 bytes --]


Or workaround could be you make declaration of 'a' global.

-----Original Message-----
From: linux-c-programming-owner@vger.kernel.org
[mailto:linux-c-programming-owner@vger.kernel.org]On Behalf Of Suciu
Flavius
Sent: Wednesday, September 15, 2004 9:06 PM
To: linux-c-programming@vger.kernel.org
Cc: gcc-help@gcc.gnu.org
Subject: Re: Memory Allocation Problem


1450 * 1450 * 8 = 16 MEGA!!!!!!!!!
So, you need a 16 mega of stack which I think is a little too much  ;)

The solution is to malloc() but check if you have 16 mega of ram ;)


Ankit Jain wrote:
>       1 #include <stdio.h>
>       2 int main()
>       3 {
>       4    double a[1450][1450];
>       5
>       6    a[1449][0] = 999;
>       7    printf( "%lf\n", a[1449][0] );
>       8    return 1;
>       9 }
>
>
> it gives segementation fault
>
> if i use malloc also it gives wrong result
>
> what to do?
>
> ankit
>
> ________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping"
> your friends today! Download Messenger Now
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Re: Memory Allocation Problem

[Suciu Flavius]

1450 * 1450 * 8 = 16 MEGA!!!!!!!!!
So, you need a 16 mega of stack which I think is a little too much  ;)

The solution is to malloc() but check if you have 16 mega of ram ;)


Ankit Jain wrote:
>       1 #include <stdio.h>
>       2 int main()
>       3 {
>       4    double a[1450][1450];
>       5
>       6    a[1449][0] = 999;
>       7    printf( "%lf\n", a[1449][0] );
>       8    return 1;
>       9 }
> 
> 
> it gives segementation fault
> 
> if i use malloc also it gives wrong result
> 
> what to do?
> 
> ankit
> 
> ________________________________________________________________________
> Yahoo! Messenger - Communicate instantly..."Ping" 
> your friends today! Download Messenger Now 
> http://uk.messenger.yahoo.com/download/index.html
> 

Re: Memory Allocation Problem

[Eljay Love-Jensen]

Hi Ankit,

Your OS probably does not provide that many megabytes of STACK space.

Allocate your enormous 2-dimensional array on the HEAP or in the BSS or in 
the DATA areas instead.

Or check out if your can adjust the size of your STACK to around 32 
MB.  That might be a linker option.  Depends on your OS.

HTH,
--Eljay

Re: Memory Allocation Problem

[Sriharsha Vedurmudi]

Hi Eljay,

  I've just discovered that the problem is not with the declaration 
(compiling and running the program in Linux RH8 with gcc 3.2).

I have run the program in a Terminal Window under Gnome GUI and a 
Non-GUI environment (basically Ctrl+Alt+F2 and F7).
The program works well under GUI terminal, but fails with a seg 
violation in non-gui environment).

 Further I traced that the program was working past the assignment 
statement "a[1449][0] = 999.343" (or something similar). It was sev 
faulting when Im trying to pass this value to a function (printf or any 
other user-defined function). Thats what I dont understand....

_Harsha_

Eljay Love-Jensen wrote:

Hi Ankit,

Your OS probably does not provide that many megabytes of STACK space.

Allocate your enormous 2-dimensional array on the HEAP or in the BSS or 
in the DATA areas instead.

Or check out if your can adjust the size of your STACK to around 32 MB.  
That might be a linker option.  Depends on your OS.

HTH,
--Eljay

Re: Memory Allocation Problem

[Eljay Love-Jensen]

Hi Sriharsha,

 >It was sev faulting when Im trying to pass this value to a function 
(printf or any other user-defined function). Thats what I dont understand....

That's usually an indicator that the available STACK is being exceeding.

(It was only a couple decades ago that I had to work with a 256 byte 
stack.  Times changes.)

--Eljay