C++ | References | Question 4

Predict the output of following C++ program.

#include<iostream>
using namespace std;

int &fun()
{
    static int x = 10;
    return x;
}
int main()
{
    fun() = 30;
    cout << fun();
    return 0;
}

(A) Compiler Error: Function cannot be used as lvalue
(B) 10
(C) 30


Answer: (C)

Explanation: When a function returns by reference, it can be used as lvalue. Since x is a static variable, it is shared among function calls and the initialization line “static int x = 10;” is executed only once.
The function call fun() = 30, modifies x to 30. The next call “cout << fun()" returns the modified value.

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