How to determine the size of a variable without using the sizeof operator in C/C++?

Question

How can I wwap value two variables without using third variable or +/- operator?

Answer 1

#include <stdio.h>
#define SIZEOF(x) (unsigned int)( (char *)(&x+1)-(char *)(&x) )

int main()
{
    int buf[4];
    printf("sizeof %d\n",SIZEOF(buf));

}

it works only for variable not for data type.

Answer 2

declare two pointers.

assign the address of the variable to these two pointers.

increment any one of the pointer.

difference in addresses of these two pointers will be the size of the variable.

Comments

Adding the sample code to Arjun's answer

#include<stdio.h>
int main(){
  int *ptr = 0;
  ptr++;
  printf("Size of int:  %d",ptr);
}

---

Mr Salil's code is more optimized. Why use 2 pointers when the purpose is served by 1 pointer.

Answer 3

Take an array of that datatype, then subtract the address of an element from the address of next element.

#include<stdio.h>
main()
{
 int a[5] = {1,2,3,4,5};
 Int size;
 size = &a[2] - &a[1];
 printf("size = %d\n",size);
}