string builder

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

First we create a new StringBuilder object from .NET. Then we loop from the last index of the string to 0, each pass we append the current char to the StringBuilder object. The append method has it own output showing some metadata, to avoid this we can ether cast [void] before the expression or pipe the output into Out-Null to suppress it. When the loop is finished, we called the ToString() method on the StringBuilder object.

StringBuilder class.

Out-Null cmdlet.

ToString method.

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([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
}
reverse in place

Reverse the char array in place.