Solution

Correct answer is 5, 10

Concept:

Pass by Reference:

In C++, when we pass variables by reference to a function, any modifications made to the parameters affect the original variables. This is useful for functions like swap, where we need to exchange the values of two variables.

Explanation:

Let's analyze the provided code step by step:
#include <iostream.h>

using namespace std;

void swap(int &x, int &y) {
    int temp = x;
    x = y;
    y = temp;
}

int main() {
    int a = 5, b = 10;
    swap(a, b); // First swap: a becomes 10, b becomes 5
    swap(a, b); // Second swap: a becomes 5, b becomes 10
    cout << a << " " << b; // Output the values of a and b
    return 0;
}

Breakdown of the code:
1. Initially, `a` is 5 and `b` is 10.
2. The first `swap(a, b)` is called:

• `x` becomes 10 (value of `b`)
• `y` becomes 5 (value of `a`)
• After the first swap, `a` becomes 10 and `b` becomes 5.

3. The second `swap(a, b)` is called:

• `x` now is 10 (the new value of `a`)
• `y` now is 5 (the new value of `b`)
• After the second swap, `a` becomes 5 and `b` becomes 10 again.

4. Finally, the output will be:

• `cout << a << " " << b;` outputs 5 10.

Therefore, the output of the program will be: 1) 5, 10.