我怎么能回到以前观察到的字符串

Question

例

String context = string.Emty; 

private void BtnForward_Click(object sender, RoutedEventArgs e) 
{ 
    //First Click 
    context = Abcd; 
    TextboxText.Text = context; //Abcd 
    //Second Click 
    TextboxText.Text = context; //new context = SADASD 
    //Third Forth Fift click new string context 
} 

//Now how i can go back 5th string 4th string 3 2 1th string 
private void BtnBack_Click(object sender, RoutedEventArgs e) 
{ 
    //Fift Forth Third Second First Observed string will show in the textbox 
    // Reverse back previous string with sequence 
    TextBoxText.Text = context; // Will reverse/Go back in sequence 
} 

我怎么能回去串

即使前进前进字符串或和反向回来。我的英语不够好解释，但如果你不明白我说的话，请让我知道

Answer 1

你需要保留之前值的参考。一种方法是在每次点击BtnForward_Click()和弹出（最近的一次）时，保存一堆字符串，以便在您点击新值时触击BtnBack_Click()。下面给出示例：

Stack context = new Stack(); 

    private void BtnForward_Click(object sender, RoutedEventArgs e) 
    { 
     // Here you would need to set the value of the Abcd based on your business logic 
     context.Push(Abcd); 
    } 

    private void BtnBack_Click(object sender, RoutedEventArgs e) 
    { 
     try 
     { 
      TextBoxText.Text = context.Peek(); // gets the most recently entered value of the stack that has not been removed (popped) 
      context.Pop();     
     } 
     catch (InvalidOperationException exc) 
     { 
      // Nothing to go back to 
     } 
    }