Option Explicit
Declare Function GetTempFileName Lib "kernel32" Alias "GetTempFileNameA" (ByVal lpszPath As String, ByVal lpPrefixString As String, ByVal wUnique As Long, ByVal lpTempFileName As String) As Long
Declare Function GetTempPath Lib "kernel32" Alias "GetTempPathA" (ByVal nBufferLength As Long, ByVal lpBuffer As String) As Long
Public Function StripTerminator(ByVal strString As String) As String
  Dim intZeroPos As Integer

  intZeroPos = InStr(strString, Chr$(0))
  If intZeroPos > 0 Then
      StripTerminator = Left$(strString, intZeroPos - 1)
  Else
      StripTerminator = strString
  End If
End Function
Public Function GetTempName() As String
  Dim ReturnVal As Long, PathBuffSize As Long, PathBuff As String
  Dim Prefix As String, FileName As String
  
  PathBuffSize = 255
  PathBuff = Space$(PathBuffSize)
  Prefix = "tmp"
  FileName = Space$(255)
  ReturnVal = GetTempPath(PathBuffSize, PathBuff)
  If ReturnVal = 0 Then
    MsgBox "Error getting directory"
    Exit Function
  End If
  PathBuff = StripTerminator(PathBuff)
  ReturnVal = GetTempFileName(PathBuff, Prefix, 0&, FileName)
  If ReturnVal = 0 Then
      MsgBox "Error getting file."
  Else
      GetTempName = StripTerminator(FileName)
  End If
End Function
Public Sub Main()
  Dim FileName As String

  FileName = GetTempName()
  If FileName <> "" Then
      Open FileName For Output As #1
          Print #1, "Created a temp file!", FileName
      Close #1
      Debug.Print FileName
  End If
End Sub