Collection was modified; enumeration operation might not exe

Question

I am working on in vb.net . Here i want to remove row of datatable using rowid. All is working fine but after remove row from datatable then i got a error message is Collection was modified; enumeration operation might not execute. I am using following code for delete row from datatable.

vb.net code:-

Dim dr As DataRow
For Each dr In dt.Rows
If dr("RowID").ToString() = dt.Rows(0)("RowID").ToString() Then
dt.Rows.Remove(dr)
End If
Next

Vulpes · Answer

Notice also that if there's a possibility that you might need to remove more than one row then you should iterate backwards through the collection using a 'for' statement. This is because each time you delete a row it alters the indices of the rows still to be examined which all move down one. If you iterate forwards you will therefore fail to examine the next element in the collection. Iterating backwards is the cleanest way to avoid this problem though you can still iterate forwards if you decrement the loop control variable before the next iteration.

Abhay Shanker · Answer

You can not change the Collection you currently loop through so while you run a for each on dt.Rows. throws that error Try as below For i = 1 To dt.Rows.Count-1 If dr(RowID).ToString() = dt.Rows(i)(RowID).ToString() Then dt.Rows.Remove(dr)

Jaganathan Bantheswaran · Answer

You cant remove a row from rows collection when you are in loop. Try to do something like this. Dim dt1 As New DataTable() dt1.Columns.Add(Name) dt1.Rows.Add(Apple) dt1.Rows.Add(Banana) dt1.Rows.Add(Orange) Dim dt2 As New DataTable() dt2.Columns.Add(Name) dt2.Rows.Add(Apple) dt2.Rows.Add(Banana) Dim rows_to_remove As New List(Of DataRow)() For Each row1 As DataRow In dt1.Rows For Each row2 As DataRow In dt2.Rows If row1(Name).ToString() = row2(Name).ToString() Then rows_to_remove.Add(row1) End If Next Next For Each row As DataRow In rows_to_remove dt1.Rows.Remove(row) dt1.AcceptChanges() Next