VB.NET
Dim dt as DateTime = DateTime.Parse(ddlMonth.SelectedItem.Text & '/' & ddlDay.SelectedItem.Text & '/' & ddlYear.SelectedItem.Text )
C#
DateTime dt = DateTime.Parse(ddlMonth.SelectedItem.Text & '/' & ddlDay.SelectedItem.Text & '/' & ddlYear.SelectedItem.Text );
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