topic Re: Alternative for sizeof operator in Operating System - OpenVMS

Alternative for sizeof operator

WSSPL — Thu, 04 Sep 2003 03:36:38 GMT

Hi All,

Is there any alternative to find the size of
data type like int, char apart from sizeof() operator.

Thanks,
Poornima.

Re: Alternative for sizeof operator

Mike Naime — Thu, 04 Sep 2003 04:04:40 GMT

How about a little more info here?

What (programing) language are you talking about?

Re: Alternative for sizeof operator

WSSPL — Thu, 04 Sep 2003 04:12:43 GMT

Hi,

I am talking about C programming language.

Thanks,
Poornima

Re: Alternative for sizeof operator

Antoniov. — Thu, 04 Sep 2003 06:16:11 GMT

Hi Poornima,
No there is not alternative to sizeof() operator in standard ANSI C.
Sizeof() is a compiletime operator can be applied to type too ,i.e. sizeof(int); runtime not call any function so sizeof() is very quick.
Why do you will not use sizeof() operator?

Antoniov

Re: Alternative for sizeof operator

WSSPL — Thu, 04 Sep 2003 08:15:52 GMT

Hi,

Actually, this is a tricky question asked
by one of my friends who is proficient is C language.

Thanks,
Poornima.

Re: Alternative for sizeof operator

Antoniov. — Thu, 04 Sep 2003 11:40:19 GMT

Hi Poormina,
if it's only a tricly question, you can use other then sizeof as follow:

#include
#define mysize sizeof
main ()
{
unsigned short size_of;
long iMyVar, *piMyVar;

piMyVar = iMyVar;
size_of = ((unsigned long) (piMyVar + 1))
- ((unsigned long) (piMyVar));
printf("%d %d %d",mysize(iMyVar), size_of, sizeof(iMyVar));
}

Above program run correctly (you can try).
1.st is a macro that redefines a sizeof operator.
In second statetemnt (size_of = ...), program evaluate address of a variable and next location; every address is casted into long and different is located in size_of variable.
Look that without unsigned long casting, different it equal to 1!!

H.T.H.
Antoniov