GATE | GATE-CS-2001 | Question 42

What is printed by the print statements in the program P1 assuming call by reference parameter passing?

Program P1()
{
   x = 10;
   y = 3;
   func1(y,x,x);
   print x;
   print y;
}
func1(x,y,z)
{
   y = y+4;
   z = x+y+z;
}

(A) 10, 3
(B) 31, 3
(C) 27, 7
(D) None of the above

Answer: (B)
Explanation: Here, we are passing the variables by call by reference. This means that the changes that we will make in the parameter would be reflected in the passed argument.

Here, the first variable passed in the function func1 (i.e., y) points to the address of the variable x.

Similarly, the second variable passed in the function func1 (i.e., x) points to the address of the variable y and the third variable passed in the function func1 (i.e., x) points to the address of the variable z.

So, we have y = y + 4 ⇒ y = 10 + 4 = 14

and z = x + y + z ⇒ z = 14 + 14 + 3 = 31

z will be returned to x. So, x = 31 and y will remain 3.

Thus, the correct choice is B.

Please comment below if you find anything wrong in the above post.
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