Swap Two Variables in One Line in C/C++

In C++, swapping two variables means exchanging the values stored in them. There can be multiple ways to implement the swapping using single line statement. In this article, we are going to learn some of the approaches to swap the values.

Example

Let's consider the following example with input and output scenario:

Input:
int a = 5;
int b = 6;

Output:
a = 6
b = 5

You can implement swapping of two variable by using the following different ways:

• Using Arithmetic Operator
• Using Tuple
• Using XOR

Swap Two Variables Using Arithmetic Operator

In C++, swapping variables using arithmetic operations is possible without temporary storage. The arithmetic operator only works with numeric types.

Example

This is the basic C++ program to swap two variables in one line using an arithmetic operator:

#include <iostream>
using namespace std;

int main() {
   int a = 5, b = 10;
   a = (a + b) - (b = a);
   cout << "a: " << a << ", b: " << b;
   return 0;
}

The above program produces the following output:

a: 10, b: 5

Swap Two Variables Using Tuple

Two variables can also be swapped using the tuples. You need to declare two variables (a and b) and assign the values (5, 10) and then use tie(a, b) = make_tuple(b, a); which creates a tuple with the values (b, a) and assigns them back to a and b respectively. This statement will swap their values. As a result, a becomes 10 and b becomes 5, and the output of the program is: a: 10, b: 5.

Example

In this example, use a C++ program to swap two variables in one line of code using a tuple:

#include <iostream>
#include <tuple>
using namespace std;

int main() {
   int a = 5, b = 10;
   tie(a, b) = make_tuple(b, a);
   cout << "a: " << a << ", b: " << b;
   return 0;
}

The above program produces the following output:

a: 10, b: 5

Swap Two Variables Using XOR

In this approach, swap variables using a bitwise XOR operation. This only works with integer types.

Following are the steps:

• First, declare two variables a and b, and assign the values 5 and 10 to them.
• Use a single line a ^= b ^= a ^= b; to swap the values of a and b using the bitwise XOR operation.
• This line performs a swap without using a temporary variable.
• Print the values of a and b after swapping.

Example

Following is the C++ program to swap two variables in one line using XOR:

#include <iostream>
using namespace std;

int main() {
   int a = 5, b = 10;
   a ^= b ^= a ^= b;
   cout << "a: " << a << ", b: " << b;
   return 0;
}

The above program produces the following output:

a: 10, b: 5