size of a datatype without using sizeof

Question

I have a data type, say X, and I want to know its size without declaring a variable or pointer of that type and of course without using sizeof oper

Answer 1

#include  

using namespace std; 

int main() 
{ 

    // take any datatype hear 
    char *a = 0; // output: 1

    int  *b = 0;  // output: 4

    long *c = 0; // output: 8

    a++;

    b++;

    c++;

    printf("%d",a);

    printf("%d",b);

    printf("%d",c);

    return 0; 
}