References - C++ Programming

Q1.

What will be the output of the following programs?

You have to predict the output result without running/executing the code.

I.

#include <iostream>

int main()
{
    int x = 1;
    int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    ref = 0;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

II.

#include <iostream>

int main()
{
    int x = 1;
    int& ref;

    ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

III.

#include <iostream>

int main()
{
    int x = 1;
    int& ref = 0;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

IV.

#include <iostream>

int main()
{
    int x = 1;
    int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    int y = 2;
    ref = y;
    y = 3;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    x = 4;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

Q2.

What will be the output of the following programs?

You have to predict the output result without running/executing the code.

I.

#include <iostream>

int main()
{
    double x = 1;
    int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

II.

#include <iostream>

int main()
{
    int x = 1;
    double& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

III. (Adv.)

#include <iostream>

int main()
{
    int x = 5;

    if (x == 5)
    {
        int& ref = x;
        
        std::cout << "x: " << x << ", ref: " << ref << '\n';
    }

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

IV. (Adv.)

#include <iostream>

int main()
{
    int x = 5;
    int& ref1 = x;
    int& ref2 = ref1;

    std::cout << "x: " << x << ", ref1: " << ref1 << ", ref2: " << ref2 << '\n';

    return 0;
}

Q3.

What will be the output of the following programs?

You have to predict the output result without running/executing the code.

I.

#include <iostream>

int main()
{
    const int x = 1;
    int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

II.

#include <iostream>

int main()
{
    const int x = 5;
    const int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

III.

#include <iostream>

int main()
{
    const int x = 5;
    const int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    ref = 7;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

IV.

#include <iostream>

int main()
{
    int x = 5;
    const int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    x = 7;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

V.

#include <iostream>

int main()
{
    int x = 5;
    const int& ref = x;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    ref = 6;

    std::cout << "x: " << x << ", ref: " << ref << '\n';

    return 0;
}

VI.

#include <iostream>

int main()
{
    const double& r1 = 5;

    std::cout << r1 << '\n';

    char c = 'a';
    const int& r2 = c;

    std::cout << r2 << '\n';

    return 0;
}

Q4.

What will be the output of the following programs?

You have to predict the output result without running/executing the code.

I.

#include <iostream>

void func(int y)
{
    std::cout << "func: y = " << y << '\n';
}

int main()
{
    int x = 5;
    
    func(x);

    std::cout << "main: x = " << x << ", y = " << y << '\n';

    return 0;
}

II.

#include <iostream>

void incrementVal(int x)
{
    x = x*4 + 5;
}

int main()
{
    int x = 7;

    std::cout << "Before incrementing: " << x << '\n';

    incrementVal(x);

    std::cout << "After incrementing: " << x << '\n';

    return 0;
}

III.

#include <iostream>

int incrementVal(int x)
{
    x = x*4 + 5;

    return x;
}

int main()
{
    int x = 7;

    std::cout << "Before incrementing: " << x << '\n';

    incrementVal(x);

    std::cout << "After incrementing: " << x << '\n';

    return 0;
}

IV.

#include <iostream>

int incrementVal(int x)
{
    x = x*4 + 5;

    return x;
}

int main()
{
    int x = 7;

    std::cout << "Before incrementing: " << x << '\n';

    x = incrementVal(x);

    std::cout << "After incrementing: " << x << '\n';

    return 0;
}

V.

#include <iostream>

void incrementVal(int& x)
{
    x = x*4 + 5;
}

int main()
{
    int x = 7;

    std::cout << "Before incrementing: " << x << '\n';

    incrementVal(x);

    std::cout << "After incrementing: " << x << '\n';

    return 0;
}

Q5.

What will be the output of the following programs?

You have to predict the output result without running/executing the code.

I.

#include <iostream>

void printValue(int& y)
{
    std::cout << y << '\n';
}

int main()
{
    int x = 5;
    printValue(x);

    const int z = 5;
    printValue(z);

    printValue(5);

    return 0;
}

II.

#include <iostream>

void printRef(const int& y)
{
    std::cout << y << '\n';
}

int main()
{
    int x = 5;
    printRef(x);

    const int z = 5;
    printRef(z);

    printRef(5);

    return 0;
}

III.

#include <iostream>

void printVal(double d)
{
    std::cout << d << '\n';
}

void printRef(const double& d)
{
    std::cout << d << '\n';
}

int main()
{
    int x = 5;

    printVal(x);
    printRef(x);

    return 0;
}

IV.

#include <iostream>

void printVal(int i)
{
    std::cout << i << '\n';
}

void printRef(const int& i)
{
    std::cout << i << '\n';
}

int main()
{
    double x = 5.6;

    printVal(x);
    printRef(x);

    return 0;
}

Q6.

Inside a text-based adventure game, we have a player whose health is full (100) when the game starts, now the player can get damaged on which his health will get decreased. So write a program to damage the player (i.e. decrease his health by amount 15 each time) using a function.

Expected Output:

THE GAME STARTS!

The player got damanged!
The updated player health: 75

The player got damanged!
The updated player health: 60

Q7.

Write a program to swap the values of two variables using a function.

Expected Output:

Enter the value of a: 8
Enter the value of b: 6

Values after swapping:
a: 6
b: 8