C | Pointer Basics | Question 2

Output of following program?

# include <stdio.h> 
void fun(int *ptr) 
{ 
    *ptr = 30; 
} 
  
int main() 
{ 
  int y = 20; 
  fun(&y); 
  printf("%d", y); 
  
  return 0; 
} 

(A) 20
(B) 30
(C) Compiler Error
(D) Runtime Error

Answer: (B)

Explanation: The function fun() expects a pointer ptr to an integer (or an address of an integer). It modifies the value at the address ptr. The dereference operator * is used to access the value at an address. In the statement ‘*ptr = 30’, value at address ptr is changed to 30. The address operator & is used to get the address of a variable of any data type. In the function call statement ‘fun(&y)’, address of y is passed so that y can be modified using its address.

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