Functions, Recursion, Parameter Passing & Classes

#include <iostream.h>
#include <conio.h>

// 1. Pass-by-Value (changes do NOT affect caller arguments)
void swapByValue(int a, int b) {
    int temp = a;
    a = b;
    b = temp;
}

// 2. Pass-by-Reference (aliases direct memory of caller arguments)
void swapByReference(int &a, int &b) {
    int temp = a;
    a = b;
    b = temp;
}

// 3. Pass-by-Pointer (dereferences memory addresses)
void swapByPointer(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

void main() {
    int x = 10, y = 20;

    clrscr();

    cout << "Initial Values: x = " << x << ", y = " << y << endl;

    // Call by Value
    swapByValue(x, y);
    cout << "\nAfter swapByValue(x, y):     x = " << x << ", y = " << y << " (Unchanged)" << endl;

    // Call by Reference
    swapByReference(x, y);
    cout << "After swapByReference(x, y): x = " << x << ", y = " << y << " (Swapped!)" << endl;

    // Call by Pointer
    swapByPointer(&x, &y);
    cout << "After swapByPointer(&x, &y): x = " << x << ", y = " << y << " (Swapped back!)" << endl;

    getch();
}