C＃将输入的文本框值减去Label值 [英] C# Subracting Inputted Textbox Value to the Label value

问题描述

我正在以Windows形式构建这些POS桌面应用程序，它几乎已经完成，但我在处理客户账单方面遇到了问题。



具体如下：   

SIMSProduct Usercontrol  



  - cart.lbl_price.Text = lbl_totalprice.Text;  

首先，购买的客户总数为lbl_totalprice.Text  

接下来，该总数用于ProcessCart表格，即cart.lbl_price.Text

  - lbl_price.Text现已成功获取lbl_totalprice.Text的值



ProcessCart表格



  - txt_amount（文本框）是用户输入应该减去lbl_price.Text失败的客户付款价值的地方。

  - lbl_totalprice.Text对应于减去的lbl_price和txt_amount的输出也是失败的。


$
注意：lbl对应Windows窗体标签



问题是当我尝试输入我的txt_amount时，假设我输入5000并且5000没有减去lbl_price的值，lbl_totalprice也等于我输入的txt_amount。在这些代码下面，我在这里做错了什么？，
我不应该做的事情？或者我忘记了什么？我希望有人能够帮助解决这些问题。谢谢

I'm building these POS Desktop application in Windows form and it's almost done but i'm having problem in processing the customer bills.

To be specific:  
SIMSProduct Usercontrol  

 - cart.lbl_price.Text = lbl_totalprice.Text;  
First the total of the customer bought is in lbl_totalprice.Text  
Next that total is used to ProcessCart Form which is the cart.lbl_price.Text
 - lbl_price.Text is now successfully getting the value of lbl_totalprice.Text

ProcessCart Form

 - txt_amount(Textbox) is where user input the pay value of customer that should be subracted to the lbl_price.Text which is fail.
 - lbl_totalprice.Text corresponds to the output of subracted lbl_price and txt_amount which is fail too


Note: lbl corresponds to Windows form Label

The problem is when i tried to input to my txt_amount, let's say i input 5000 and that 5000 is not subracting the value of lbl_price, also the lbl_totalprice is equal to what i type to txt_amount. Below these code, What I've done wrong here ?, something that i should not made? or i forgot something ?. I hope someone would be able to help in these matter. Thank you

public partial class SIMSProduct : UserControl
    {
        ITEMCount item;
        ProcessCart cart;
        public SIMSProduct()
        {
            InitializeComponent();         
        }
    
     private void btn_process_Click(object sender, EventArgs e)
        {
            cart = new ProcessCart();
            cart.Show();
            cart.lbl_price.Text = lbl_totalprice.Text; 
        }
    }

    public partial class ProcessCart : Form
    {     
        public ProcessCart()
        {
            InitializeComponent();
        }
     private void txt_amount_TextChanged(object sender, EventArgs e)
        {
            decimal value1;
            decimal value2;
            decimal value3;
            if (decimal.TryParse(lbl_price.Text.Trim(), out value1))
            {
                Total = Convert.ToInt32(lbl_price.Text);            
            }
            if (decimal.TryParse(txt_amount.Text.Trim(), out value2))
            {

                Paid = Convert.ToDecimal(txt_amount.Text);          
            }
            if (decimal.TryParse(lbl_totalprice.Text.Trim(), out value3))
            {
                Change = Convert.ToDecimal(lbl_totalprice.Text);
            }
            Change = Paid - Total;

        }
    }

推荐答案

问候Miracle_23。

Greetings Miracle_23.

我不确定我是否完全理解这个问题，但至少有一个明显的问题。

I'm not sure I completely understand the issue, but there is at least one obvious problem.

你正在计算两次改变。我确定第一个不对。

You are calculating Change twice. I'm sure the first one can't be right.

            if (decimal.TryParse(lbl_totalprice.Text.Trim(), out value3))
            {
                // This looks wrong. Are you sure this should be Change here, and not something else?
                Change = Convert.ToDecimal(lbl_totalprice.Text);
            }
            Change = Paid - Total; // You calculate Change here, which looks like the above line can't be right.

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