winform文本框即输即选

private void textBox2_TextChanged( object sender, EventArgs e )
        {
            // 文本框即输即选方法一
            //this.textBox2.SelectionStart = 0;  可省
            this.textBox2.SelectAll();
        }

        private void textBox2_KeyDown( object sender, KeyEventArgs e )
        {
            this.textBox2.SelectionStart = this.textBox2.Text.Length;
        }

        private void textBox2_KeyUp( object sender, KeyEventArgs e )
        {
            // 文本框即输即选方法二
            //this.textBox2.SelectionStart = 0;   可省      
            this.textBox2.SelectAll();
        }