Excel Automation and Detection in VB6

[bkh_vb1]

My application uses Excel automation. Therefore, I reference the Excel Object Library. I have 2 questions...

1) How can I detect the presence of Excel on the system where my application is being used -- essentially to warn the user that the portion of the application that automates Excel will not work?

2) Since my application references the Excel Object Library, if the application is installed on a system that does not have Excel installed, will the application even run if Excel is not present?

Thanks

[pclement]

Originally posted by bkh_vb1
My application uses Excel automation. Therefore, I reference the Excel Object Library. I have 2 questions...

1) How can I detect the presence of Excel on the system where my application is being used -- essentially to warn the user that the portion of the application that automates Excel will not work?

Couple of different ways to do this. Since you're already using automation you could simply trap the error that will occur when you call CreateObject. Not elegant but you're certain to determine whether automation with Excel is available.

You can also use the FindExecutable API function call to locate the path to the Excel executable:

Declare Function FindExecutable Lib "shell32.dll" Alias "FindExecutableA" (ByVal lpFile As String, ByVal lpDirectory As String, ByVal lpResult As String) As Long

Function ExcelPath() As String

Dim sDummyFile As String
Dim sDir As String
Dim sFilePath As String * 255

sDummyFile = "e:\My Documents\book1.xls"

If FindExecutable(sDummyFile, sDir, sFilePath) > 32 Then
    ExcelPath = TrimNull(sFilePath)
End If

End Function

Function TrimNull(item As String) As String

    Dim pos As Integer
   
    pos = InStr(item, Chr$(0))
    
    If pos Then
          TrimNull = Left$(item, pos - 1)
    Else: TrimNull = item
    End If
  
End Function

2) Since my application references the Excel Object Library, if the application is installed on a system that does not have Excel installed, will the application even run if Excel is not present?

Your application will run but as soon as you attempt to instantiate Excel objects it will fail.

In addition, if the application is to support multiple versions of Excel you will probably want to consider using late binding by not referencing the type library and declaring all Excel variables as Object.