AddExtension属性如何在C#2.0中工作？

尝试只用"csv"了DefaultExt-还,你应该是using这(是IDisposable):

        using (SaveFileDialog sfd = new SaveFileDialog())
        {
            sfd.AddExtension = true;
            sfd.DefaultExt = "csv";
            sfd.Filter = "Comma Separated(*.csv)|*.*";
            if (sfd.ShowDialog() == DialogResult.OK)
            {
                // Do my file saving
            }
        }