C++ sizeof Operator



C++ sizeof Operator

  • sizeof is a compile-time operator used to calculate the size of data type or variable.
  • sizeof operator will return the size in integer format.
  • sizeof is a keyword.
  • sizeof operator can be nested.

Syntax of sizeof Operator:

sizeof(data type)

Data type include variables, constants, classes, structures, unions, or any other user defined data type.

Examples of sizeof operator:

Size of Data Types

#include <iostream>
using namespace std;
 
int main()
{
   cout << "Size of int : " << sizeof(int) << endl;
   cout << "Size of long int : " << sizeof(long int) << endl;
   cout << "Size of float : " << sizeof(float) << endl;
   cout << "Size of double : " << sizeof(double) << endl;
   cout << "Size of char : " << sizeof(char) << endl;
  
   return 0;
}

Output:

Size of int : 4
Size of long int : 4
Size of float : 4
Size of double : 8
Size of char : 1

Size of Variables:

#include <iostream>
using namespace std;
 
int main()
{
   int i;
   char c;
 
   cout << "Size of variable i : " << sizeof(i) << endl;
   cout << "Size of variable c : " << sizeof(c) << endl;
  
   return 0;
}

Output:

Size of variable i : 4
Size of variable c : 1

Size of Constant:

#include <iostream>
using namespace std;
 
int main()
{
   cout << "Size of integer constant: " << sizeof(10) << endl;
   cout << "Size of character constant : " << sizeof('a') << endl;
  
   return 0;
}

Output:

Size of integer constant: 4
Size of character constant : 1

Nested sizeof operator:

#include <iostream>
using namespace std;
 
int main()
{
   int num1,num2;
   cout << sizeof(num1*sizeof(num2));
     return 0;
}

Output:

4