计算燃料的平均成本 [英] Calculating avg cost of fuel

问题描述

我试图获得每次旅行购买燃料的平均费用。



我的代码片段如下：

 Private Sub calc（）
 
 Dim 
a，f1，f2，f3，f4，f5，f6 As Decimal 
试试
 f1 = CDec（IIf（tbTruckFuelPurchased.Text.Trim =，0D，tbTruckFuelPurchased.Text.Trim））
 f2 = CDec（IIf（tbReeferFuelPurchased.Text.Trim =，0D，tbReeferFuelPurchased。 Text.Trim））
 f3 = CDec（IIf（tbDEFPurchased.Text.Trim =，0D，tbDEFPurchased.Text.Trim））
 f4 = CDec（IIf（tbGalsPurch.Text.Trim = ，0D，tbGalsPurch.Text.Trim））
 f5 = CDec（IIf（tbREF_Gals.Text.Trim =，0D，tbREF_Gals.Text.Trim））
 f6 = CDec（IIf（tbFuelCostAvg） .Text.Trim =，0D，tbFuelCostAvg.Text.Trim））
 Catch ex As Exception 
'如果发生计算错误，请显示错误消息框
 Dim frm As New MeMsgCalcError（可执行程序'计算DIM语句'定义区域中的错误。）
 frm.Show（）
结束尝试
 
 
'计算此加载的平均燃料成本
尝试
a = f1 \ f4 
 tbFuelCostAvg.Text = a.ToString（C2）
 Catch ex As Exception 
'如果发生计算错误，请显示错误消息框
 Dim frm As New MeMsgCalcError（例如，此加载的平均燃料成本计算错误。）
 frm.Show（）
结束尝试

这个错误注意到：

错误BC30512 选项严格打开禁止隐式转换从'Decimal'到'Long'。



如上面错误消息中所述，Option Strict为On，需要如此。



我如何购买所购买的燃料总量（tbTruckFuelPurchased（货币））并将购买的总燃料加仑（tbGalsPurch（整数加上3位小数）除以平均每加仑成本？显然我正在寻找钱返回值舍入到2位小数。



我不理解从十进制到长错误消息的转换。



我尝试了什么：



查看代码和尝试的消息。

解决方案

< blockquote>问题在于这一行：

 a = f1 \ f4 

\ 运算符执行整数除法，并返回适合于操作数类型的整数类型：

\运算符（Visual Basic） [ ^ ]



您需要使用 / 运算符执行标准除法：

 a = f1 / f4 

由于所有fn变量都声明为Decimal，并且代码段中只有一个其他赋值，因此必须是以下行：

 a = f1 \ f4 

这意味着 a 必须是 Long 和option strict不会让你只将一个Decimal值赋给Long变量，因为它必须丢弃小数点右边的任何数据。为了做到这一点 - Long是一个整数数据类型，不能保存小数值。

所以检查并更改 a to Decimal，或将Decimal强制转换为Long值：



 a =  CLng （f1）\  CLng （f4）





BTW：帮自己一个忙，不要使用变量名，如 f1 ， f2 或 a - 使用更长的名称来描述值的含义。它使你的代码更具可读性和可靠性！



[edit] changign a won; t help - 我忘记了\运算符如果选项会抛出错误Stricty打开并提供浮点值： https：// msdn .microsoft.com / zh-cn / library / 0e16fywh.aspx？f = 255& MSPPError = -2147217396 [ ^ ] [/ edit]




I am attempting to get the average cost of fuel purchased per trip.

My code snippets are as follows:



Private Sub calc()

        Dim 
            a, f1, f2, f3, f4, f5, f6 As Decimal
        Try
            f1 = CDec(IIf(tbTruckFuelPurchased.Text.Trim = "", 0D, tbTruckFuelPurchased.Text.Trim))
            f2 = CDec(IIf(tbReeferFuelPurchased.Text.Trim = "", 0D, tbReeferFuelPurchased.Text.Trim))
            f3 = CDec(IIf(tbDEFPurchased.Text.Trim = "", 0D, tbDEFPurchased.Text.Trim))
            f4 = CDec(IIf(tbGalsPurch.Text.Trim = "", 0D, tbGalsPurch.Text.Trim))
            f5 = CDec(IIf(tbREF_Gals.Text.Trim = "", 0D, tbREF_Gals.Text.Trim))
            f6 = CDec(IIf(tbFuelCostAvg.Text.Trim = "", 0D, tbFuelCostAvg.Text.Trim))
        Catch ex As Exception
            'If a calculation error occurs, show Error message box
            Dim frm As New MeMsgCalcError(ex, "Error in 'Calculation DIM Statement' Defining Area.")
            frm.Show()
        End Try


        'Calculate Average Cost of Fuel this Load
        Try
            a = f1 \ f4
            tbFuelCostAvg.Text = a.ToString("C2")
        Catch ex As Exception
            'If a calculation error occurs, show Error message box
            Dim frm As New MeMsgCalcError(ex, "Calculation Error in 'Average Cost of Fuel this Load.'")
            frm.Show()
        End Try



This errors out noting:
Error BC30512 Option Strict On disallows implicit conversions from 'Decimal' to 'Long'.

As noted above in the error message, Option Strict is On and needs to be so.

How might I take the total fuel purchased (tbTruckFuelPurchased (currency)) and divide total fuel gallons purchased (tbGalsPurch (whole number plus 3 decimals) to end up with an average cost per gallon? Obviously I am looking for a "money" returned value rounded to 2 decimals.

I am not understanding the conversion from Decimal to Long error message.

What I have tried:

See message for code and tries.

解决方案

The problem is with this line:

a = f1 \ f4

The \ operator performs an integer division, and returns an integer type appropriate for the types of the operands:
\ Operator (Visual Basic)[^]

You need to perform a standard division, using the / operator:

a = f1 / f4




Since all of your "fn" variables are declared as Decimal, and there is only one other assignment in the code snippet, it has to be this line:

a = f1 \ f4

Which means that a has to be a Long and option strict won't let you just assign a Decimal value to a Long variable since it would have to throw away any data to the right of the decimal point. in order to do it - Long is an integer data type that can't hold fractional values.
So either check and change the definition of a to Decimal, or cast the Decimal to a Long value:

a = CLng(f1) \ CLng(f4)

BTW: do yourself a favour and don't use variable names like f1, f2, or a - use longer names that are more descriptive of what the value holds. It makes your code a lot more readable and more reliable!

[edit]changign a won;t help - I forgot the the \ operator throws the error if Option Stricty is on and you supply floating point values: https://msdn.microsoft.com/en-us/library/0e16fywh.aspx?f=255&MSPPError=-2147217396[^] [/edit]




这篇关于计算燃料的平均成本的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！