如何通過RepeatButton增加和減少一百個數字？

Question

您可以通過一個通過以下代碼增加和減少數字。

以下代碼是okey。

<Window x:Class="WpfApplication1.MainWindow" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Title="MainWindow" Height="350" Width="400"> 
<Grid> 
    <RepeatButton Width="100" Height="40" HorizontalAlignment="Left" Name="btnRemove" Content="Remove" Click="btnRemove_Click" /> 
    <TextBox Width="150" Height="40" Name="txtDisplay" TextAlignment="Center" Text="5000" MaxLength="5" /> 
    <RepeatButton Width="100" Height="40" HorizontalAlignment="Right" Name="btnAdd" Content="Add" Click="btnAdd_Click" /> 
</Grid> 
</Window> 

...

Namespace WpfApplication1 

Partial Public Class MainWindow 

    Public counter As Integer = 5000 

    Private Sub btnAdd_Click(sender As Object, e As RoutedEventArgs) 
     txtDisplay.Text = (System.Threading.Interlocked.Increment(counter)).ToString() 
    End Sub 

    Private Sub btnRemove_Click(sender As Object, e As RoutedEventArgs) 
     txtDisplay.Text = (System.Threading.Interlocked.Decrement(counter)).ToString() 
    End Sub 

End Class 

End Namespace 

問：

如何提高和百降低數字嗎？

Answer 1

這個怎麼樣？

Private Sub btnAdd_Click(sender As Object, e As RoutedEventArgs) 
    counter += 100 
    If (counter > 6000) Then 
     counter = 6000 
    End If 
    txtDisplay.Text = counter.ToString() 
End Sub 

Private Sub btnRemove_Click(sender As Object, e As RoutedEventArgs) 
    counter -= 100 
    If (counter < 0) Then 
     counter = 0 
    End If 
    txtDisplay.Text = counter.ToString() 
End Sub 

沒有理由在這裏使用System.Threading.Interlocked.Increment因爲事件處理程序總是相同的線程上執行。

Answer 2

所以你的問題是關於線程安全遞增/遞減？您可以使用Interlocked.Add：

Private Sub btnAdd_Click(sender As Object, e As RoutedEventArgs) 
    txtDisplay.Text = System.Threading.Interlocked.Add(counter, 100).ToString() 
End Sub 

Private Sub btnRemove_Click(sender As Object, e As RoutedEventArgs) 
    txtDisplay.Text = System.Threading.Interlocked.Add(counter, -100).ToString() 
End Sub