Swapping of Two Numbers in C++

Swap Two Numbers in C++ Using Temporary Variable

Let’s take an interesting example to understand this concept:

Suppose we have three boxes. Box 1 has an apple, Box 2 has an orange, and Box 3 is empty. We need to interchange the fruits in Box 1 & 2 with the help of Box 3.

So we follow the below steps...

1. First, we take an apple from Box 1 and place it inside Box 3.
2. Now Box 1 is empty, take an orange out of Box 2 and place it inside Box 1.
3. Now Box 2 is empty, take an apple out of Box 3 and place it inside Box 2.
4. Finally, items of both Boxes are now exchanged, i.e., swapped.

Algorithm

• Start: Begin the process.
• Initialize Variables: Define three variables, a, b, and temp. Assign values to a and b that you want to swap.
• Swap Numbers:
  • Assign the value of a to temp.
  • Assign the value of b to a.
  • Assign the value of temp to b.
• Display Swapped Numbers: Print the values of a and b after the swap.
• End: The process is complete.

Program to Swap Two Numbers using Temporary Variable

Output:

Three variables are created to perform the swapping in which the contents of the first variable, a, are stored in the temp variable. Then, the contents of the second variable b are stored in the first variable a. Finally, the contents of the temp variable are stored back to the second variable b, which completes the swapping operation.

Complexity

Time Complexity: O(1), as only constant time operations are done. Space Complexity: O(1), as no extra space has been used.

Swap Numbers Without using Temporary Variables (using * and / only)

Algorithm

• Start: Initiate the process.
• Initialize Variables:
  • Define two variables, a and b.
  • Assign the desired values to a and b.
• Check for Zero:
  • Ensure neither a nor b is zero, as division by zero is undefined.
• Swap Numbers:
  • Multiply a by b and store the result in a.
    • Now, a holds the product of the initial values of a and b.
  • Divide the new value of a by b and store the result in b.
    • Now, b holds the initial value of a.
  • Divide the new value of a by the new value of b and store the result in a.
    • Now, a holds the initial value of b.
• Display Swapped Numbers:
  • Output the swapped values of a and b.
• End: Conclude the process.

Program to Swap Two Numbers Without using Temporary Variable

Output:

Let us understand the workings of the above program:

1. Initially, a = 6 and b = 2.
2. Then, we multiply a and b and store them in the program using a = a * b. This means a = 6 * 2. So, a = 12 now.
3. Then, we divide a and b and store them using b = a / b. This means b = 12 / 2. So, b = 6 now.
4. Finally, we divide a and b again using a = a / b. This means a = 12 / 6. Therefore, a = 2.

Complexity

Time Complexity: O(1), as only constant time operations are done. Space Complexity: O(1), as no extra space has been used.

Swap Numbers Without Using Temporary Variables (using + and - only)

Algorithm

• Start: Initiate the swapping process.
• Initialize Variables:
  • Define two variables, a and b.
  • Assign the initial values to a and b that you wish to swap.
• Swap Numbers:
  • Add the values of a and b and store the result back in a.
  • Subtract the value of b from a and store the result in b.
  • Subtract the value of a from b and store the result back in a.
• Display Swapped Numbers:
  • Output the new values of a and b, which have now been swapped.
• End: Conclude the swapping process.

Program to Swap Two Numbers Without using Temporary Variable

Output:

Let us now understand the workings of the above program:

1. Initially, a = 6 and b = 2.
2. Then, we add a and b and store them in the program using a = a + b. This means a = 6 + 2. So, a = 8 now.
3. Then, we subtract a and b and store them in the program using b = a - b. This means b = 8 - 2. So, b = 6 now.
4. Finally, we use a = a - b. This means a = 8 - 6. Therefore, a = 2.

Complexity

Time Complexity: O(1), as only constant time operations are done. Space Complexity: O(1), as no extra space has been used.

Swap numbers using “swap” function

The function std::swap() is a built-in function in the C++ Standard Template Library (STL) that swaps the value of two variables.

Syntax of swap() Function

Parameters

The swap function takes two parameters, a and b, which are to be swapped. These parameters can be of any data type.

Return Values

The swap function does not return anything, as it is used to swap two numbers.

C++ Program to Swap Two Numbers Using Inbuilt swap() Function

Output

Related Topics

• Java Program to Swap Two Numbers
• Python Program to Swap Two Numbers