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When foreach in Excel goes wrong

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This seems like a reasonable piece of code:

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

so does this:

foreach Excel.CustomProperty prop in worksheet.CustomProperties
{
Console.WriteLine(prop.Name);
}

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: https://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

  • Anonymous
    November 18, 2004
    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.)
  • Anonymous
    November 23, 2004
    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
  • Anonymous
    January 21, 2009
    PingBack from http://www.keyongtech.com/4019085-worksheet-customproperties