TestDotNetVersion.ps1

Function Test-NetInstalled {

    param(
        [Parameter(Position = 1, mandatory = $false)]
        [String] $DotNetVersion
    )
    [Int] $RegEditDotNet | Out-Null
    [bool] $RequiredVersion = $true
    
    $dWord = Get-ChildItem "hklm:SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\" | Get-ItemPropertyValue -Name Release 
    if ($DotNetVersion) {
        switch ($DotNetVersion) {
            "4.5" { $RegEditDotNet = 378389} 
            "4.5.1" { $RegEditDotNet = 378675}
            "4.5.2" { $RegEditDotNet = 379893}
            "4.6" { $RegEditDotNet = 393295}
            "4.6.1" { $RegEditDotNet = 394254}
            "4.6.2" { $RegEditDotNet = 394802}
            "4.7" { $RegEditDotNet = 460798}
            "4.7.1" { $RegEditDotNet = 461308}
            default {$RegEditDotNet = 0}
        }
        if ($dWord -lt $RegEditDotNet -or $RegEditDotNet -eq 0 ) {
            Write-Error "You must have .NET $DotNetVersion installed on this machine to continue!"
            $RequiredVersion = $false
        }
        else {
            Write-Host "At least $DotNetVersion is installed!" -ForegroundColor White -BackgroundColor Red
        }
    }

    switch ($dWord) {
        378389 { $DotNetVersion = "4.5"  }
        378675 { $DotNetVersion = "4.5.1"}
        379893 { $DotNetVersion = "4.5.2" }
        393295 { $DotNetVersion = "4.6"   }
        394254 { $DotNetVersion = "4.6.1" }
        394802 { $DotNetVersion = "4.6.2" }
        460798 { $DotNetVersion = "4.7"   }
        461308 { $DotNetVersion = "4.7.1" }
    }
    $DotNetInfo = @{ DotNetVersion = $DotNetVersion; DWORD = $dWord[0]; RequiredVersion = $RequiredVersion}
    return $DotNetInfo
}

$huh = Test-NetInstalled 
Write-Host ".NET Version is $($huh.DotNetVersion), DWORD Value is $($huh.DWORD) and Required Version is $($huh.RequiredVersion)" -ForegroundColor White -BackgroundColor DarkGreen

$huh2 = Test-NetInstalled -DotNetVersion "4.6.1"
Write-Host ".NET Version is $($huh2.DotNetVersion), DWORD Value is $($huh2.DWORD) and Required Version is $($huh2.RequiredVersion)" -ForegroundColor White -BackgroundColor DarkMagenta

$huh3 = Test-NetInstalled -DotNetVersion "5.6.1" -ErrorAction Stop
Write-Host ".NET Version is $($huh3.DotNetVersion), DWORD Value is $($huh3.DWORD) and Required Version is $($huh3.RequiredVersion)" -ForegroundColor White -BackgroundColor DarkCyan

$huh4 = Test-NetInstalled -DotNetVersion "5.6.1" -ErrorAction Stop
Write-Host ".NET Version is $($huh4.DotNetVersion), DWORD Value is $($huh4.DWORD) and Required Version is $($huh4.RequiredVersion)" -ForegroundColor White -BackgroundColor DarkCyan