Hui buddies can anybody let me know how can i find size of a variable without using sizeof() operator?

Hi all,
As an exercise, I am trying to figure out the size of a long in my
machine without using the sizeof operator. I came up with the
following:

This works fine but I am afraid that if the code is being run in a
machine where it doesn't use 2's compliment. It will not work so I
came up with another function:

This works regardless of what machine the code is running.

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Before me is Endless Possibility,
Around me is Boundless Opportunity,
Why should I fear!

The sizeof operator returns the size in bytes of its operand. Whether the result of sizeof is unsigned int or unsigned long is implementation defined—which is why the declaration of malloc above ducked the issue by omitting any parameter information; normally you would use the stdlib.h header file to declare malloc correctly. Here is the example done portably:

#include <stdlib.h> /* declares malloc() */
float *fp;

fp = (float *)malloc(sizeof(float));

The operand of sizeof only has to be parenthesized if it's a type name, as it was in the example. If you are using the name of a data object instead, then the parentheses can be omitted, but they rarely are.

#include <stdlib.h>

int *ip, ar[100];
ip = (int *)malloc(sizeof ar);

In the last example, the array ar is an array of 100 ints; after the call to malloc (assuming that it was successful), ip will point to a region of store that can also be treated as an array of 100 ints.

The fundamental unit of storage in C is the char, and by definition

sizeof(char)

is equal to 1.