单击按钮后冻结表单

Question

我有关于付款按钮的问题。 我在建筑之前没有遇到错误，但在建立并单击付款按钮后，它会挂起。我认为它是因为lblTotalPrice.text，但我不知道如何解决它。

public partial class Form1 : Form 
{ 
    int totalCost; 
    public double holDer; 



    public Form1() 
    { 
     InitializeComponent(); 
     this.cbo1.Items.AddRange(new object[] { "Lechon Kawali - 200", "Bicol Express - 300" 
      ,"Adobo - 350" }); 

    } 

    private void btnAdd_Click(object sender, EventArgs e) 
    { 
     lb1.Items.Add(cbo1.SelectedItem); 

     lb1.SelectedIndex = lb1.SelectedIndex ; 

     int z = 0; 

     if (cbo1.SelectedIndex == 0) 
     { 
      z = z + 1; 
     } 

     if (cbo1.SelectedIndex == 1) 
     { 
      z = z + 2; 
     } 
     if (cbo1.SelectedIndex == 2) 
     { 
      z = z + 3; 
     } 

     switch(z) 
     { 
      case 1: 
       totalCost = totalCost + 200; 
       break; 
      case 2: 
       totalCost = totalCost + 300; 
       break; 
      case 3: 
       totalCost = totalCost + 350; 
       break; 
     } 

     lblSubTotalCost.Text = ("Php " + totalCost.ToString()); 


    } 

    private void btnDelete_Click(object sender, EventArgs e) 
    { 
     int deleteCost = 0; 
     int itemCost = 0; 
     foreach (int selectedIndex in lb1.SelectedIndices) 
     { 
      itemCost = int.Parse(lb1.Items[selectedIndex].ToString().Split('-')[1]); 
      deleteCost += itemCost; lb1.Items.RemoveAt(selectedIndex); 
     } 

     totalCost = totalCost - deleteCost; 

     lblSubTotalCost.Text = ("Php " + totalCost.ToString()); 

     lb1.Items.Remove(lb1.SelectedItem); 
     if (lb1.Items.Count > 0) 
     { 
      lb1.SelectedIndex = 0; 
     } 
     else 
      MessageBox.Show("No orders"); 


    } 

    private void lblVAT_TextChanged(object sender, EventArgs e) 
    { 
     Add(); 
    } 
    private void lblSubTotalCost_TextChanged(object sender, EventArgs e) 
    { 
     multiply(); 
     Add(); 
    } 
    public void multiply() 
    { 
     int a; 
     double b = 0.12; 
     bool Valid = int.TryParse(totalCost.ToString(), out a); 

     if (Valid) 
      lblVAT.Text = (a * b).ToString(); 
     else 
      lblVAT.Text = "No VAT entered"; 

    } 

    private void lbTotalPrice_TextChanged(object sender, EventArgs e) 
    { 
     Add(); 
    } 


    public void Add() 
    { 
     int a; 
     int b; 

     bool AValid = int.TryParse(totalCost.ToString(), out a); 
     bool BValid = int.TryParse(lblVAT.Text, out b); 

     if (AValid && BValid) 
     { 
      lblTotalPrice.Text = ("Php " + (a + b).ToString()); 

     } 


    } 

    private void btnPayment_Click(object sender, EventArgs e) 
    { 
     holDer = double.Parse(tbPayment.Text) - double.Parse(lblTotalPrice.Text); 
     MessageBox.Show("Change: " + holDer.ToString()); 

    } 

} 

Answer 1

我怀疑这是因为lblTotalPrice_TextChanged事件处理程序调用Add()然后改变lblTotalPrice.Text属性，从而导致事件再次触发，广告-infinitum？

Answer 2

正如您在评论中所述，您的问题不是您的应用程序挂起，而是问题在于您得到Input string was not in a correct format异常。

，它似乎是从该块：

private void btnPayment_Click(object sender, EventArgs e) 
{ 
    holDer = double.Parse(tbPayment.Text) - double.Parse(lblTotalPrice.Text); 
    MessageBox.Show("Change: " + holDer.ToString()); 
} 

由于它是一个不是很复杂的代码，你的问题似乎当你您铸造文本框，以双待。请确保您使用的是双值的正确分离和你没有任何奇怪的字符在tbPayment

尝试使用的TryParse方法：

double res; 

if(double.TryParse(tbPayment.Text, out res)) 
{ 
    holDer = res - double.Parse(lblTotalPrice.Text); 
    MessageBox.Show("Change: " + holDer.ToString()); 
} 
else 
{ 
    MessageBox.Show("Input a correct format"); 
}