您好，有谁知道我如何处理system.formatexception [英] Hello, does anyone know how I can handle a system.formatexception

问题描述

我的代码中没有错误，至少我在错误列表中看到的错误。但每次我运行我的代码时，都会出现一个system.formatexception。我是编程和VB.NET的新手，所以我可以做些什么来解决这个问题会有所帮助。



我尝试过：

 Private Sub Button1_Click（发送者作为对象，e作为EventArgs）处理Button1.Click 
 Dim Mealcost作为新Cmeal 
 Mealcost.Tea = Mealcost.pTea * Double.Parse（txtTea.Text）
 Mealcost.Soft_Drink = Mealcost.pSoft_Drink * Double.Parse（txtSoft_Drink.text）
 Mealcost.Coffee = Mealcost.pCoffee * Double.Parse（txtCoffee.text）
 Mealcost.Fruit_Juice = Mealcost.pFruit_Juice * Double.Parse（txtFruit_Juice.text）
 Mealcost.Water = Mealcost.pWater * Double.Parse（txtWater.text）
 
 
 Mealcost.Cake = Mealcost.pCake * Double.Parse（txtCake.text）
 Mealcost.Muffin = Mealcost.pMuffin * Double.Parse（txtMuffin.text）
 Mealcost.Waffles = Mealcost.pWaffles * Double.Parse（txtWaffles.Text）
 
 
 
 Mealcost.Hamburger = Mealcost.pHamburger * Double.Parse（txtHa） mburger.text）
 Mealcost.Fish_Chips = Mealcost.pFish_Chips * Double.Parse（txtFish_Chips.text）
 Mealcost.Meat_Pap = Mealcost.pMeat_Pap * Double.Parse（txtMeat_Pap.text）
 Mealcost。 Bunny_Chow = Mealcost.pBunny_Chow * Double.Parse（txtBunny_Chow.text）
 Mealcost.Isitambu = Mealcost.pIsitambu * Double.Parse（txtIsitambu.Text）
 
 
 Mealcost.Greek_Salad = Mealcost.pGreek_Salad * Double.Parse（txtGreek_Salad.text）
 Mealcost.Potatoe_Salad = Mealcost.pPotatoe_Salad * Double.Parse（txtPotatoe_Salad.text）
 Mealcost.Fruit_Salad = Mealcost.pFruit_Salad * Double.Parse（txtFruit_Salad。文本）
 
 Dim iSubtotal As Double = Mealcost.GetAmount 
 Dim iVat As Double = Mealcost.GetVat 
 Dim iTotal As Double = iSubtotal + iVat 
 
 vat.Text = FormatCurrency（iVat）
 sub_total.Text = FormatCurrency（iSubtotal）
 total.Text = FormatCurrency（iTotal）
 
 
 End Sub 
 

解方案

你写给货币格式的方法;为双打做同样的事情。



您可以在例程和任何默认/错误处理中执行Double.TryParse;返回一个有效的数字。



这样你就可以限制你需要编写的代码量。

I have no errors in my code, at least from what I can see on the error list. but every time I run my code it comes up with a system.formatexception. am new to coding and VB.NET so any advise on what I can do to solve this problem would help.

What I have tried:

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim Mealcost As New Cmeal
    Mealcost.Tea = Mealcost.pTea * Double.Parse(txtTea.Text)
    Mealcost.Soft_Drink = Mealcost.pSoft_Drink * Double.Parse(txtSoft_Drink.text)
    Mealcost.Coffee = Mealcost.pCoffee * Double.Parse(txtCoffee.text)
    Mealcost.Fruit_Juice = Mealcost.pFruit_Juice * Double.Parse(txtFruit_Juice.text)
    Mealcost.Water = Mealcost.pWater * Double.Parse(txtWater.text)


    Mealcost.Cake = Mealcost.pCake * Double.Parse(txtCake.text)
    Mealcost.Muffin = Mealcost.pMuffin * Double.Parse(txtMuffin.text)
    Mealcost.Waffles = Mealcost.pWaffles * Double.Parse(txtWaffles.Text)



    Mealcost.Hamburger = Mealcost.pHamburger * Double.Parse(txtHamburger.text)
    Mealcost.Fish_Chips = Mealcost.pFish_Chips * Double.Parse(txtFish_Chips.text)
    Mealcost.Meat_Pap = Mealcost.pMeat_Pap * Double.Parse(txtMeat_Pap.text)
    Mealcost.Bunny_Chow = Mealcost.pBunny_Chow * Double.Parse(txtBunny_Chow.text)
    Mealcost.Isitambu = Mealcost.pIsitambu * Double.Parse(txtIsitambu.Text)


    Mealcost.Greek_Salad = Mealcost.pGreek_Salad * Double.Parse(txtGreek_Salad.text)
    Mealcost.Potatoe_Salad = Mealcost.pPotatoe_Salad * Double.Parse(txtPotatoe_Salad.text)
    Mealcost.Fruit_Salad = Mealcost.pFruit_Salad * Double.Parse(txtFruit_Salad.Text)

    Dim iSubtotal As Double = Mealcost.GetAmount
    Dim iVat As Double = Mealcost.GetVat
    Dim iTotal As Double = iSubtotal + iVat

    vat.Text = FormatCurrency(iVat)
    sub_total.Text = FormatCurrency(iSubtotal)
    total.Text = FormatCurrency(iTotal)


End Sub

解决方案

You wrote a method to format Currency; do the same for doubles.

You can do the Double.TryParse in the routine and any default / error handling; returning a valid number.

That way you limit the amount of code you need to write.

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