Functions (User-defined & Built-in) Interview Questions

    Question 1: C++ Function Declaration

    Which of the following is the correct way to declare a function in C++ that returns an integer and takes no arguments?

    Question 2: C++ Function Definition

    What is the correct way to define a function named add that takes two integers and returns their sum?

    Question 3: C++ Guess the Output – Function Return

    What will be the output of the following C++ code?

    #include <iostream>
using namespace std;

int square(int x) {
    return x * x;
}

int main() {
    cout << square(4);
    return 0;
}

    Question 4: C++ Function Overloading

    Which of the following demonstrates valid function overloading in C++?

    int add(int a, int b);
int add(float a, float b);

    Question 5: C++ Guess the Output – Pass by Value

    What will be the output of the following code?

    #include <iostream>
using namespace std;

void change(int x) {
    x = 20;
}

int main() {
    int a = 10;
    change(a);
    cout << a;
    return 0;
}

    Question 6: C++ Pass by Reference

    Which of the following correctly demonstrates pass by reference in C++?

    Question 7: C++ Default Arguments

    Which function declaration is valid with default arguments?

    Question 8: C++ Inline Functions

    What is the purpose of an inline function in C++?

    Question 9: C++ Guess the Output – Recursion

    What will be the output of the following program?

    #include <iostream>
using namespace std;

int factorial(int n) {
    if (n == 0) return 1;
    return n * factorial(n - 1);
}

int main() {
    cout << factorial(4);
    return 0;
}

    Question 10: C++ Function Prototypes

    Why are function prototypes used in C++?