如何在vb.net中正确地进行简单的数学计算? [英] How to do a simple maths percetange calculation correctly in vb.net?

问题描述

可以将这个等式重新构造为格式正确的字符串吗?

Can this equation be reworked to a correctly formatted string?

Dim Total = MyNumber / 100 * MyVAT

产生错误:

"Input string was not in a correct format" 

推荐答案

您应该将Option Strict设置为on.然后，由于MyNumber是一个字符串(如您所述)，因此永远不会编译.

You should really set Option Strict to on. Then this would never compile since MyNumber is a string(as you've commented).

首先应确保输入为数字，例如使用Decimal.TryParse:

You should first ensure that the input is numeric, for example with Decimal.TryParse:

Dim Total As Decimal
Dim num As Decimal 
If Decimal.TryParse(MyNumber, num) Then
    Total = num / 100 * MyVAT
End If

现在，您可以使用Decimal.ToString(format)将其转换为具有所需格式的字符串.例如(假设您想要两位小数):

Now you can use Decimal.ToString(format) to convert it to a string with the desired format. For example(assuming you want two decimal places):

Dim output As String = Total.ToString("N2")

标准数字格式字符串

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