reverse in place

Reverse String
Reverse String in PowerShell 
function ReverseString([char[]] $String) {
    $last = $String.Count - 1
    $mid  = [Math]::Ceiling($String.Count / 2)
    for ($i = 0; $i -lt $mid; $i++) {
        $String[$i], $String[$last - $i] = $String[$last - $i], $String[$i]
    }
    -join $String
}

This is another approach dealing with char array, so to cheat here a bit, first let cast the string into an array of char straight from parameter. To reverse an array here, what essentially happen is that we swap the values of the first and last indices, travelling inward up to the middle index of the array. For this method, we use a for loop to loop from 0 to the middle index, and for each step of the loop we swap values. After the loop has completed, use -join operator to concatenate this char array back into one single string.

Visualize here:

[1,2,3,4,5] <- original array, 3 is the middle

 v       v
[5,2,3,4,1] <- first pass

   v   v
[5,4,3,2,1] <- second pass, array got reversed

For loop.

6th Nov 2024 · Found it useful?

Other Approaches to Reverse String in PowerShell

Other ways our community solved this exercise
function ReverseString([string] $String) {
    $charArray = $String.ToCharArray()
    [array]::Reverse($charArray)
    -join $charArray
}
built-in reverse

Using the built-in reverse method of the array class. 

function ReverseString([string] $String) {
    -join $String[$String.Length..0]
}
join range operator

Reverse the string using foreach loop. 

function ReverseString([string] $String) {
    $strBuilder = [System.Text.StringBuilder]::new()
    foreach ($i in ($String.Length - 1)..0) {
        [void] $strBuilder.Append($String[$i])
    }
    $strBuilder.ToString()
}
string builder

Build a new string using string builder.