PowerShell Script to Swap Two Numbers Easily

In PowerShell, swap two numbers using a temporary variable like this: $temp = $a; $a = $b; $b = $temp.

Examples

Inputa=5, b=10

Outputa=10, b=5

Inputa=0, b=0

Outputa=0, b=0

Inputa=-3, b=7

Outputa=7, b=-3

How to Think About It

To swap two numbers, think of holding one number temporarily so it doesn't get lost when you overwrite it. Use a temporary variable to store the first number, then assign the second number to the first, and finally assign the temporary value to the second number.

Algorithm

1

Store the value of the first number in a temporary variable.

2

Assign the value of the second number to the first number.

3

Assign the value stored in the temporary variable to the second number.

4

Print or return the swapped values.

Code

powershell

$a = 5
$b = 10
$temp = $a
$a = $b
$b = $temp
Write-Output "After swapping: a=$a, b=$b"

Output

After swapping: a=10, b=5

Dry Run

Let's trace swapping a=5 and b=10 through the code

1

Store first number in temp

$temp = 5

2

Assign second number to first

$a = 10

3

Assign temp to second number

$b = 5

Variable	Value
$temp	5
$a	10
$b	5

Why This Works

Step 1: Temporary storage

Using $temp = $a saves the original value of $a so it is not lost.

Step 2: Overwrite first variable

Assigning $a = $b puts the second number into the first variable.

Step 3: Restore second variable

Assigning $b = $temp completes the swap by putting the original first number into the second variable.

Alternative Approaches

Using tuple assignment

powershell

$a = 5
$b = 10
($a, $b) = @($b, $a)
Write-Output "After swapping: a=$a, b=$b"

This method is shorter and uses PowerShell's array unpacking to swap without a temporary variable.

Using arithmetic operations

powershell

$a = 5
$b = 10
$a = $a + $b
$b = $a - $b
$a = $a - $b
Write-Output "After swapping: a=$a, b=$b"

Swaps numbers without extra variables but only works with numeric values and can cause overflow.

Complexity: O(1) time, O(1) space

Time Complexity

Swapping two numbers involves a fixed number of operations, so it runs in constant time O(1).

Space Complexity

Only a few variables are used, so space complexity is constant O(1).

Which Approach is Fastest?

All approaches run in O(1) time; tuple assignment is concise, arithmetic avoids extra variables but has risks.

Approach	Time	Space	Best For
Temporary variable	O(1)	O(1)	Clear and safe swapping
Tuple assignment	O(1)	O(1)	Concise and modern PowerShell
Arithmetic operations	O(1)	O(1)	No extra variables but only numeric and safe values