C#Winform下限制TextBox只能输入数字

C#的winform中控制TextBox中只能输入数字

private void textBox3_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
//阻止从键盘输入键
e.Handled = true;
if(e.KeyChar>='0' && e.KeyChar <='9')
{
e.Handled = false;
}

}


多条件的：

private void TxtUser_KeyPress(object sender, KeyPressEventArgs e)
{
//阻止从键盘输入键
e.Handled = true;

if ((e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar == (char)8))
{

if ((e.KeyChar == (char)8)) { e.Handled = false; return; }
else
{
int len = TxtUser.Text.Length;
if (len < 5)
{
if (len == 0 && e.KeyChar != '0')
{
e.Handled = false; return;
}
else if(len == 0)
{
MessageBox.Show("编号不能以0开头！"); return;
}
e.Handled = false; return;
}
else
{
MessageBox.Show("编号最多只能输入5位数字！");
}
}
}
else
{
MessageBox.Show("编号只能输入数字！");
}


}