IPRange-ToArray

using namespace System.Collections.Generic

function IPRange-ToArray{
    [CmdletBinding()]
    [OutputType([psobject])]
    param(
        [Parameter(
            Mandatory = $true,
            HelpMessage = 'Starting IP Address',
            ValueFromPipeline = $true,
            Position = 0
        )]
        [ipaddress]$Start,

        [Parameter(
            Mandatory = $true,
            HelpMessage = 'Ending IP Address',
            ValueFromPipeline = $true,
            Position = 1
        )]
        [ipaddress]$End
    ) #param block end

    $s_oct = [PSCustomObject] @{
        a = $Start.GetAddressBytes()[0]
        b = $Start.GetAddressBytes()[1]
        c = $Start.GetAddressBytes()[2]
        d = $Start.GetAddressBytes()[3]
        ab = $Start.GetAddressBytes()[0..1] -join '.'
        abc = $Start.GetAddressBytes()[0..2] -join '.'
    }

    $e_oct = [PSCustomObject] @{
        a = $End.GetAddressBytes()[0]
        b = $End.GetAddressBytes()[1]
        c = $End.GetAddressBytes()[2]
        d = $End.GetAddressBytes()[3]
        ab = $End.GetAddressBytes()[0..1] -join '.'
        abc = $End.GetAddressBytes()[0..2] -join '.'
    }

    $ip_list = [System.Collections.Generic.List[PSObject]]::new()

    # check if there is a difference in the c octets.
    if($s_oct.c -eq $e_oct.c){
        $s_oct.d..$e_oct.d | ForEach-Object { $ip_list.Add($($s_oct.abc + ".$_")) }
    }else{

        # add 1st range
        $s_oct.d..255 | ForEach-Object { $ip_list.Add($($s_oct.abc + ".$_")) }

        # check if the difference between the c octets is greater than 1
        #if greater, sequencial loop adding ranges
        if([math]::Abs($s_oct.c - $e_oct.c) -gt 1){
            $tmp = $s_oct.c + 1
            while($tmp -lt $e_oct.c){
                1..255 | ForEach-Object { $ip_list.Add($($s_oct.ab + ".$tmp.$_")) }
                $tmp += 1
            }
        }

        # add last range
        1..$e_oct.d | ForEach-Object { $ip_list.Add($($e_oct.abc + ".$_")) }
    }
    return $ip_list
}

Clear-Host

IPRange-ToArray '192.168.0.100' '192.168.2.10'