UpDownBase.Select(Int32, Int32) 方法

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

在数字显示框（也称为 up-down 控件）中选择一个文本范围，该范围指定起始位置和要选择的字符数。

public:
 void Select(int start, int length);

public void Select (int start, int length);

override this.Select : int * int -> unit

Public Sub Select (start As Integer, length As Integer)

参数

start

Int32

要选择的第一个字符的位置。

length

Int32

要选择的总字符数。

示例

下面的代码示例使用派生类 NumericUpDown。 此代码要求 NumericUpDown 已在窗体上创建了控件和 Button ，并且 System.Drawing 命名空间已添加为引用。 在 Click 按钮的 事件上，控件中 NumericUpDown 文本的点大小增加。 这会提示控件调整其 PreferredHeight 属性，以便控件中所有文本都可见。 用户输入新值并离开NumericUpDown控件后，文本将从字符串值转换为数值，并验证是否在 和 Maximum 值之间Minimum。 如果值无效， MessageBox 则会显示 并显示错误，并且 Select 方法将选择文本，以便用户可以输入新值。

void numericUpDown1_Leave( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   /* If the entered value is greater than Minimum or Maximum,
         select the text and open a message box. */
   if ( (System::Convert::ToInt32( numericUpDown1->Text ) > numericUpDown1->Maximum) || (System::Convert::ToInt32( numericUpDown1->Text ) < numericUpDown1->Minimum) )
   {
      MessageBox::Show( "The value entered was not between the Minimum andMaximum allowable values.\nPlease re-enter." );
      numericUpDown1->Focus();
      numericUpDown1->Select(0,numericUpDown1->Text->Length);
   }
}

void button1_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
   int varPrefHeight1;
   
   /* Capture the PreferredHeight before and after the Font
         is changed, and display the results in a message box. */
   varPrefHeight1 = numericUpDown1->PreferredHeight;
   numericUpDown1->Font = gcnew System::Drawing::Font( "Microsoft Sans Serif",12.0,System::Drawing::FontStyle::Bold );
   MessageBox::Show( String::Format( "Before Font Change: {0}\nAfter Font Change: {1}", varPrefHeight1, numericUpDown1->PreferredHeight ) );
}

private void numericUpDown1_Leave(Object sender,
                                  EventArgs e)
{
   /* If the entered value is greater than Minimum or Maximum,
      select the text and open a message box. */
   if((System.Convert.ToInt32(numericUpDown1.Text) > numericUpDown1.Maximum) ||
      (System.Convert.ToInt32(numericUpDown1.Text) < numericUpDown1.Minimum))
   {
      MessageBox.Show("The value entered was not between the Minimum and" +
         "Maximum allowable values." + "\n" + "Please re-enter.");
      numericUpDown1.Focus();
      numericUpDown1.Select(0, numericUpDown1.Text.Length);
   }
}
   
private void button1_Click(Object sender,
                           EventArgs e)
{
   int varPrefHeight1;
   
   /* Capture the PreferredHeight before and after the Font
      is changed, and display the results in a message box. */
   varPrefHeight1 = numericUpDown1.PreferredHeight;
   numericUpDown1.Font = new System.Drawing.Font("Microsoft Sans Serif",
      12F, System.Drawing.FontStyle.Bold);
   MessageBox.Show("Before Font Change: " + varPrefHeight1.ToString() +
      "\n" + "After Font Change: " + numericUpDown1.PreferredHeight.ToString());
}

Private Sub numericUpDown1_Leave(sender As Object, e As EventArgs)
    ' If the entered value is greater than Minimum or Maximum,
    ' select the text and open a message box. 
    If (System.Convert.ToInt32(numericUpDown1.Text) > numericUpDown1.Maximum) Or _
        (System.Convert.ToInt32(numericUpDown1.Text) < numericUpDown1.Minimum) Then
        MessageBox.Show("The value entered was not between the Minimum and " & _
            "Maximum allowable values." & Microsoft.VisualBasic.ControlChars.Cr & _
            "Please re-enter.")
        numericUpDown1.Focus()
        numericUpDown1.Select(0, numericUpDown1.Text.Length)
    End If
End Sub    

Private Sub button1_Click(sender As Object, e As EventArgs)
    Dim varPrefHeight1 As Integer
    
    ' Capture the PreferredHeight before and after the Font
    ' is changed, and display the results in a message box. 
    varPrefHeight1 = numericUpDown1.PreferredHeight
    numericUpDown1.Font = New System.Drawing.Font("Microsoft Sans Serif", _
        12F, System.Drawing.FontStyle.Bold)
    MessageBox.Show("Before Font Change: " & varPrefHeight1.ToString() & _
        Microsoft.VisualBasic.ControlChars.Cr & "After Font Change: " & _
        numericUpDown1.PreferredHeight.ToString())
End Sub

注解

Select当旋转框获得焦点或属性未通过数据验证时Text，可以使用 方法。 在派生类中添加 方法的 ValidateEditText 验证代码时，请在验证失败时调用 Select 方法。

另请参阅

• ValidateEditText()