Get-NetComputers.ps1

function Get-NetComputers {

    [cmdletbinding()]
    Param(

        [Parameter(Mandatory = $True,
                   Position =0,
                   HelpMessage ="Specify the first IP in the range(s).")]
        [String]$StartIP,

        [Parameter(Mandatory = $False,
                   Position =1,
                   HelpMessage ="Enter the last IP in the range(s).")]
        [String]$EndIP,

        [Parameter(Mandatory = $False,
        HelpMessage ="Specify the subnets you wish to scan.")]
        [Alias('Multiple')]
        [String[]]$SubnetArray,

        [Parameter(Mandatory = $False,
        HelpMessage ="Set this if you wish to output the results of the scan to a csv file.")]
        [Switch]$OutCSV

    )

    BEGIN{
    [Int]$Count = 0
    [Int]$OctetCount = 0
    [String]$Subnet = $Null
    [int]$StartLastOctet = $Null
    [int]$EndLastOctet = $Null
    [Int]$SubnetCount = 0
    $IPQueue = New-Object System.Collections.Queue
    $Ping = New-Object System.Net.Networkinformation.Ping
    $ComputerList = New-Object System.Collections.Generic.List[System.Object]
    if($OutCSV){
        $OutPath = "C:\Users\clafleur\Documents\NetComputers.csv"
        Remove-Item -Path $OutPath -Force -EA SilentlyContinue
        $FileHandle = New-Object System.IO.StreamWriter -Arg $OutPath
        $FileHandle.AutoFlush = $True
        }
    }

    PROCESS{

    if($SubnetArray -EQ $Null){
    for([Int]$i = 0; $i -LT $StartIP.Length; $i++){
        if($StartIP[$i] -EQ "."){
           $OctetCount++
        }
        if ($OctetCount -EQ 3) {
            $Subnet = $StartIP
            [String] $Temp = $StartIP.Substring($i)
            $Temp = $Temp.Trim(".")
            $StartLastOctet = [convert]::ToInt32($Temp, 10)
            $OctetCount = 0
                break
        }
    }

    for([Int]$j = 0; $j -LT $EndIP.Length; $j++){
        if($EndIP[$j] -EQ "."){
                $OctetCount++
            }
        if ($OctetCount -EQ 3) {
            [String] $Temp = $EndIP.Substring($j)
            $Temp = $Temp.Trim(".")
            $EndLastOctet = [convert]::ToInt32($Temp, 10)
            $OctetCount = 0
                break
        }
    }

        for([Int]$k = 0; $k -LT $Subnet.Length; $k++){
            if($Subnet[$k] -EQ "."){
           $OctetCount++
            }
            if ($OctetCount -EQ 3) {
            [String] $Temp = $Subnet.Substring(0, $k)
            $Subnet = $Temp + "."
            $OctetCount = 0
                break
            }
        }

        while($StartLastOctet -LE $EndLastOctet){
            [String]$Temp = $Subnet + $StartLastOctet
            $IPQueue.Enqueue($Temp)
            $StartLastOctet++
        }
     }

     if($SubnetArray -NE $Null){

        $StartLastOctet = $StartIP
        $EndLastOctet = $EndIP
        $TempOctet = $StartLastOctet

        while($SubnetCount -LT $SubnetArray.Count){
            [String]$Temp = $SubnetArray[$SubnetCount] + "." + $StartLastOctet
            $IPQueue.Enqueue($Temp)
            $StartLastOctet++
            if($StartLastOctet -EQ $EndLastOctet){
                [String]$Temp = $SubnetArray[$SubnetCount] + "." + $StartLastOctet
                $IPQueue.Enqueue($Temp)
                $SubnetCount++
                $StartLastOctet = $TempOctet
                }
        }
     }

   <#function Multithreader{

    $RunspacePool = [RunspaceFactory]::CreateRunspacePool(1,50)
    $RunspacePool.Open()

    $Count = $IPQueue.Count

    $Jobs = @()

    for($i = 0; $i -LT $Count; $i++){
        $Job = [PowerShell]::Create()
        $Job.RunspacePool = $RunspacePool
        $Job.AddScript({Get-ComputerInfo})
        $Jobs += New-Object -TypeName PSObject -Property @{
            Thread = $Job
            Handle = $Job.BeginInvoke()
        }
    }

    foreach ($Job in $Jobs){
        if($Job.Handle.IsCompleted -EQ $True){
            $Job.Thread.EndInvoke($Job.Handle)
            $Job.Thread.Dispose()
        }
    }

    $RunspacePool.Close() | Out-Null
    $RunspacePool.Dispose() | Out-Null
  }#>

   function Get-ComputerInfo {
        $NumIPs = $IPQueue.Count

        if($NumIPs -EQ 1){Write-Host 1}

        for([Int]$i = 0; $i -LT $NumIPs; $i++){
          $ComputerInfo = New-Object -TypeName PSObject
          $IP = $IPQueue.Dequeue()
          $Test = $Ping.Send($IP, 1, .1)
          if($Test.Status -EQ 'Success'){
            try{
                $HostN = [System.Net.DNS]::GetHostEntry("$IP")
                $HostN = $HostN.HostName


                for([Int]$j = 0; $j -LT $HostN.Length; $j++){
                    if($HostN[$j] -EQ "."){
                        [String] $Temp = $HostN.Substring(0, $j)
                        $HostN = $Temp
                    }
                }

                $ComputerInfo | Add-Member -Type NoteProperty -Name IPAddress -Value $IP -Force
                $ComputerInfo | Add-Member -Type NoteProperty -Name HostName -Value $HostN -Force

                if($OutCSV){
                $FileHandle.WriteLine("$IP, $HostN")
                    }
                }
                catch{
                    $ComputerInfo | Add-Member -Type NoteProperty -Name IPAddress -Value $IP -Force
                    $ComputerInfo | Add-Member -Type NoteProperty -Name HostName -Value 'HostName could not be resolved' -Force
                    if($OutCSV){
                        $FileHandle.WriteLine($ComputerInfo.IPAddress + ", " + $ComputerInfo.HostName)
                    }
                }
                $ComputerList.Add($ComputerInfo)
             }
          else{
            Start-Sleep -Milliseconds .1
          }
        }
      }
    }
     END{
        Get-ComputerInfo
        if($OutCSV){
            $FileHandle.Flush()
            $FileHandle.Dispose()
            $FileHandle.Close()
        }
        return $ComputerList
        }
}