C++ Exercises: Swap the values of two variables not using third variable

Last update on August 11 2025 12:58:16 (UTC/GMT +8 hours)

Swap Variables Without Temp

Write a C++ program that swaps two variables without using a third variable.

Visual Presentation:

C++ Exercises: Swap the values of two variables not using third variable

Sample Solution:

C++ Code :

#include <iostream> // Including the input-output stream header file

using namespace std; // Using the standard namespace

int main() // Start of the main function
{
	cout << "\n\n Swap two numbers without using third variable:\n"; // Displaying the purpose of the program
	cout << "---------------------------------------------------\n";

	int num1, num2, temp; // Declaring three integer variables to hold numbers

	cout << " Input 1st number : "; // Prompting the user to input the first number
	cin >> num1; // Taking the first number as input from the user

	cout << " Input 2nd number : "; // Prompting the user to input the second number
	cin >> num2; // Taking the second number as input from the user

	num2 = num2 + num1; // Swapping logic: adding both numbers and storing the result in num2
	num1 = num2 - num1; // Swapping logic: subtracting the original num1 from the updated num2 and storing the result in num1
	num2 = num2 - num1; // Swapping logic: subtracting the updated num1 from the updated num2 and storing the result in num2

	// Displaying the swapped numbers
	cout << " After swapping the 1st number is : " << num1 << "\n";
	cout << " After swapping the 2nd number is : " << num2 << "\n\n";
}

Sample Output:

Swap two numbers without using third variable:                        
---------------------------------------------------                    
 Input 1st number : 25                                                 
 Input 2nd number : 20                                                 
 After swapping the 1st number is : 20                                 
 After swapping the 2nd number is : 25

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to swap two numbers without using a third variable by applying bitwise XOR operations.
Write a C++ program that swaps two integer variables using arithmetic operators and verifies the swap with a printed output.
Write a C++ program to swap two numbers using a combination of multiplication and division without a temporary variable.
Write a C++ program that demonstrates swapping of two variables without a temporary variable, then prints both values before and after the swap.

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