public static extern int ExpandEnvironmentStrings([MarshalAs(UnmanagedType.LPTStr)] String source, [Out] StringBuilder destination, int size);

<DllImport("kernel32.dll", EntryPoint:="ExpandEnvironmentStringsW", SetLastError:=true, CharSet:=CharSet.Unicode)> _

Public Function ExpandEnvironmentStrings(<MarshalAs(UnmanagedType.LPTStr)> lpSrc As String , _

Public Declare Function ExpandEnvironmentStrings Lib "kernel32.dll" Alias "ExpandEnvironmentStringsW" (ByVal lpSrc As String, ByVal lpDst As String, ByVal nSize As Long) As Long

this is already deprecated in win32, you should use ExpandEnvironmentStrings

This is basically the inverse of ExpandEnvironmentStrings or [Environment.ExpandEnvironmentVariables]. Only Microsoft knows why this inverse function didn't make it's way into the framework.

        /// To expand the environment variable references, use the ExpandEnvironmentStrings function.