Question

c#中一个程序编写完成后如何修改命名空间?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TextBox
{
private void btnstart_KeyPress(object sender, KeyPressEventArgs e)
{
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TextBox textBox = sender as TextBox; 此处出现错误。
错误 1 “TextBox”是“命名空间”，但此处被当做“类型”来使用
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
if(e.KeyChar<'0' || e.KeyChar>'9')
{
e.Handled = true;
}

if (btnstart.SelectionStart==0 && e.KeyChar=='0')
{
e.Handled = true;
}

if (e.KeyChar== 8)
{
e.Handled = false;
}
}

private void l(object sender, EventArgs e)
{

}
}
}

Answer 1

 System.Windows.Forms.TextBox textBox = sender as System.Windows.Forms.TextBox;