static extern bool PathAppend([In, Out] StringBuilder pszPath, string pszMore);

<DllImport("shlwapi.dll", EntryPoint:="PathAppendW", SetLastError:=True, CharSet:=CharSet.Unicode)> _

Public Function PathAppend(<MarshalAs(UnmanagedType.LPTStr)>pszPath As System.Text.StringBuilder, _

Public Declare Function PathAppend Lib "shlwapi" Alias "PathAppendA" _

This is similar, but not identical, to PathAppend and [Path.Combine]. For example, combining "C:\foo" with "\bar" yields "C:\bar" rather than "C:\foo\bar" or "\bar" respectively.