Test and Create Directory in PowerShell

#
# Creates a directory named "archive" relative to the currently executing script's directory,
# if it doesn't already exist.
#

$scriptDir = Split-Path $script:MyInvocation.MyCommand.Path
$archiveDir = "$scriptDir\archive"

if (!(Test-Path -Path $archiveDir))
{
    Write-Host "Creating archive directory at: '$archiveDir'"
    New-Item -ItemType directory -Path $archiveDir
}
else
{
    Write-Host "Archive directory already exists: '$archiveDir'"
}

### Function Example

function Delete-If-Exists
{
    param([string] $dir)

    if (!(Test-Path -Path $dir))
    {
        Write-Host "Directory does not exist '$dir'"
    }
    else
    {
        Write-Host "Deleting '$dir'"
        Remove-Item $dir -recurse
    }
}

Delete-If-Exists "C:\path\to\delete"

# Or using .NET
if (![System.IO.Directory]::Exists($tempDir)) {[System.IO.Directory]::CreateDirectory($tempDir)}