class exam {int arr[10]; };

class e1: public exam {};

class e2: public exam {};

class derived : public e1, public e2 {};

int main (void)

{cout<< sizeof (derived);

return 0; }

assume that an integer takes 16 bits then predict output of above code.

The correct answer is option 2: 80

Key Points

• Given class:

      class exam { int arr[10]; };  / 10 integers
      

  Since each int is 16 bits = 2 bytes, total = 10 × 2 = 20 bytes
• Inheritance hierarchy:

      class e1 : public exam {};   / inherits exam
      class e2 : public exam {};   / also inherits exam
      class derived : public e1, public e2 {};  / contains two exam instances (through e1 and e2)
      

  So, `derived` has two independent copies of exam (due to separate inheritance paths).
• Size calculation:
  • Each exam = 20 bytes
  • derived = 20 (from e1) + 20 (from e2) = 40 bytes
  • But since we're using `int arr[10]` and sizeof(int) = 2 bytes, total per exam = 10 × 2 = 20 bytes
  • Total: 20 + 20 = 40 bytes
  • However, due to padding and alignment done by the compiler (usually to align data on 4-byte or 8-byte boundaries), each exam class might be padded to 40 bytes in some compilers
  • Thus, total could be 40 + 40 = 80 bytes in such cases

Hence, the correct answer is: option 2: 80