When foreach in Excel goes wrong

This seems like a reasonable piece of code:

For Each oCell As Excel.Range In Me.Range("a1:b5")
  oCell.Value = "test"

so does this:

foreach Excel.CustomProperty prop in worksheet.CustomProperties

Unfortunately, when you run this code you will get a "Missing member" exception.  Some collections in Excel can't be "for-eached" over.  To do "foreach" the CLR has to get an enumerator from the collection.  The CLR and CLR interop expect to find a _NewEnum member method on the collection.  Some Excel collections have a _NewEnum member that is implemented as a property and not a method. 

There is a KB on this issue:  http://support.microsoft.com/?kbid=328347

Clearly this is not happy, but there is a work around--use a for next loop and get members of the collection using Item with a 1-based index.

Hopefully, this is an issue we will get fixed in VS 2005 so that all Excel collections, even the ones that have a _NewEnum member that is a property, can be for-eached.

Comments (3)
  1. Brad says:

    Which of these fail? Both? Or just the second?

    (I ask because the first one looks fine. I use code like that all the time.)

  2. Jon Peltier says:

    I don’t know this dot net stuff, but in regular VBA, the official way to write that For Each is:

    For Each oCell In Me.Range("a1:b5").Cells

    Usually Excel figures out what you meant, but you could also have meant .Rows or .Columns.

    – Jon

    XL MVP

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