Operands for sizeof operator

The sizeof operator is used to return the size of its operand, in bytes. This operator always precedes its operand. The operand either may be a data-type or an expression. Let’s look at both the operands through proper examples.

1. type-name: The type-name must be specified in parentheses.

   
   

   
   
   

   sizeof(type - name)

   Let’s look at the code:
   

   C

   
   

   
   
   

   #include <stdio.h>  int main()  {      printf("%lu\n", sizeof(char));      printf("%lu\n", sizeof(int));      printf("%lu\n", sizeof(float));      printf("%lu", sizeof(double));     return 0;  }

   C++

   
   

   
   
   

   #include <iostream>  using namespace std;     int main()  {      cout << sizeof(char)<<"\n";      cout << sizeof(int)<<"\n";      cout << sizeof(float)<<"\n";      cout << sizeof(double)<<"\n";      return 0;  }

   Output:

   1
   4
   4
   8
   

2. expression: The expression can be specified with or without the parentheses.

   
   

   
   
   

   // First type sizeof expression    // Second type sizeof(expression)

   The expression is used only for getting the type of operand and not evaluation. For example, below code prints value of i as 5 and the size of i a
   

   C

   
   

   
   
   

   #include <stdio.h>    int main() {     int i = 5;     int int_size = sizeof(i++);        // Displaying the size of the operand     printf("\n size of i = %d", int_size);        // Displaying the value of the operand     printf("\n Value of i = %d", i);        getchar();     return 0; }

   C++

   
   

   
   
   

   #include <iostream> using namespace std;    int main() {     int i = 5;     int int_size = sizeof(i++);        // Displaying the size of the operand     cout << "\n size of i = " << int_size;        // Displaying the value of the operand     cout << "\n Value of i = " << i;        return 0; }    // This code is contributed by SHUBHAMSINGH10

   Output:

   size of i = 4
    Value of i = 5
   

References:
http://www.gnu.org/software/gnu-c-manual/gnu-c-manual.html#The-sizeof-Operator