All the different ways to get the Computer Name

GetComputerName.ps1

# ENV variable
$env:COMPUTERNAME
  # Note: this is limited to 15 characters

# native C++
hostname.exe
  # Note: this shows the full name     <<=====

# environment class
[System.Environment]::MachineName
  # Note: this is limited to 15 characters

# WMI
(Get-CimInstance -ClassName Win32_ComputerSystem).Name
  # Note: this is limited to 15 characters
(Get-CimInstance -ClassName Win32_ComputerSystem).DNSHostName
  # Note: this shows the full name     <<=====

# CIM
(Get-CIMInstance -ClassName CIM_ComputerSystem).Name
  # Note: this is limited to 15 characters

# P/Invoke using KERNEL32.dll
$code = @'
using System.Runtime.InteropServices;
public class PInvokeKernel {
    [DllImport("KERNEL32.dll", CharSet = CharSet.Auto, BestFitMapping = false)]
    public extern static int GetComputerName([Out]System.Text.StringBuilder nameBuffer,ref int bufferSize);
}
'@
Add-Type -TypeDefinition $code
[int]$Length = 0
[PInvokeKernel]::GetComputerName($null,[ref]$Length) | Out-Null
$ComputerName = [System.Text.StringBuilder]::new($Length)
[PInvokeKernel]::GetComputerName($ComputerName,[ref]$Length) | Out-Null
$ComputerName.ToString()
   # Note: this is limited to 15 characters

# P/Invoke using WSOCK32.DLL
$code = @'
using System.Runtime.InteropServices;
public class PInvokeSocket {
    [DllImport("WSOCK32.DLL", SetLastError = true)]
    public static extern long gethostname(System.Text.StringBuilder name, int nameLen);
}
'@
Add-Type -TypeDefinition $code
$ComputerName = [System.Text.StringBuilder]::new(256)
[PInvokeSocket]::gethostname($ComputerName,256) | Out-Null
$ComputerName.ToString()
   # Note: this ????

# .NET DNS
[System.Net.Dns]::GetHostName()
   # Note: this shows the full name    <<=====

# Windows Forms
Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.SystemInformation]::ComputerName
  # Note: this is limited to 15 characters