问计算网格中的列数

EN

<Button Click="addcolumn" Grid.Column="{Binding Path=Colsize}">+</Button>

public int colsize = 0;
        public int Colsize
        {
            get { return colsize; }
            set { colsize = value; }
        }
public void addcolumn(Object sender,  RoutedEventArgs e)
        {
            maincolumn = new ColumnDefinition();
            maincolumn.Width = new GridLength(50);
            maingrid.ColumnDefinitions.Add(maincolumn);
            colsize = maingrid.ColumnDefinitions.Count;
        }