size of non local variables

Anmol P. Paralkar
Tue Dec 1 00:17:00 GMT 2009

On Tue, 1 Dec 2009, ranjith kumar wrote:

> thanks.
> But the problem is that I am debugging a large code.
> It contains many  non local variables.
> It is said that 2 global variables are of large size(char arrays).
> I cant do 'print sizeof' on all non local variables.
> Isn't there another method.

Hello Ranjith Kumar,

  I assume that you want to be able to tell which are your largest global variables?

  PS: I am not entirely sure that your question pertains to GDB - but I could be
  wrong. I am including the following in the hope that it'll be of help. (Kindly help
  keep the discussion from getting off-topic for the GDB list, thank you).

$ cat hello.c
#include <stdio.h>

int u = 128;
int x;
char c;
char globals[1<<16];
int n = 1024;
char c0 = 'a';

int main(void) {

 	printf ("hello, world!\n");
 	return 0;
$ gcc hello.c -o hello
$ nm --extern-only --print-size --size-sort --radix=d hello | gawk '$3 ~ /[bBdD]/'
0000000006359264 0000000000000001 B c
0000000006293636 0000000000000001 D c0
0000000006293632 0000000000000004 D n
0000000006293628 0000000000000004 D u
0000000006293696 0000000000000004 B x
0000000006293728 0000000000065536 B globals


  On the other hand, GDB Guru's, is there a way one could get a list of a program's
  symbols into a list and map over that list, a function that takes a symbol as an
  argument and returns an integer representing it's size? etc...

  I tried looking at the Python support documentation to see if this could be done
  easily, but could not really tell (I've never used GDB's Python support nor Python).

  Is there a mini-tutorial somewhere that has an example of getting started with
  using GDB's Python support? I tried trying out the Greet snippet here:
  but I'm not sure what I'm doing wrong.

  Thanks very much.


> Thanks in advance.
> On 12/1/09, Anmol P. Paralkar <> wrote:
>> On Tue, 1 Dec 2009, ranjith kumar wrote:
>>> Hi,
>>> I know that gdb will print non local variable names and file name in
>>> which they are defined ,
>>> when we run 'info variables' command.
>>> Is it possible to print the size of the non local varibles also?
>>> like the size of 'int global[100]' is 400bytes that????
>>> thanks in advance.
>> Hello Ranjith Kumar,
>>   You could do:
>> (gdb) print sizeof(global)
>> $1 = 400
>>   --
>>   - that's an instance of GDB's functionality to evaluate expressions in the
>> source language with the 'print' command.
>>   See 'Examining Data' in the User Manual:
>> Best Regards,
>> Anmol.

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