需要VB做... while循環來計算平均值

Question

編碼新手。上週我有一個項目要求用戶輸入4個等級，然後計算所有4個等級的平均值，並且最低等級的平均值下降（已經轉換成btw）。要求是For Next循環和Do While循環來計算平均值。我使用For Next循環來獲得4個等級的總和，然後計算平均值。

Declare variables, constant, and array 
     Const intMAX_SUBSCRIPT As Integer = 3 
     Dim intGrades(intMAX_SUBSCRIPT) As Integer 
     Dim intTotal As Integer = 0  'holds the total of grades 
     Dim dblAverage As Double  'holds the average of all 4 grades 
     Dim intCount As Integer   'loop counter 
     Dim intLowest As Integer  'holds the lowest score 

     'assign grades to array slots 
     intGrades(0) = CInt(txtGrade1.Text) 
     intGrades(1) = CInt(txtGrade2.Text) 
     intGrades(2) = CInt(txtGrade3.Text) 
     intGrades(3) = CInt(txtGrade4.Text) 

     'Loop to calculate average in grades array 
     'get total of all grades 
     For intCount = 0 To (intGrades.Length - 1) 
      intTotal += intGrades(intCount) 

     Next 
     'use floating-point div to find average 
     dblAverage = intTotal/intGrades.Length 

這工作正常。然後我用以下找到最低年級：

 intLowest = intGrades(0) 

     'Search for the lowest grade in the array 
     For intCount = 1 To (intGrades.Length - 1) 
      If intGrades(intCount) < intLowest Then 
       intLowest = intGrades(intCount) 
      End If 
     Next 

這也工作，因爲它應該。現在，我遇到了這個問題：做一個儘管計算新的平均值與最低的分數下降。這是我需要幫助的地方：

 Dim intNewTotal As Integer = 0 'holds the new total of the 3 highest grades 
     Dim dblNewAverage As Double 'holds the new average with the lowest score dropped 
     Dim intNewCount As Integer = 0 'loop counter 

     Do While intNewTotal <= (intTotal - intLowest) 
      intNewTotal = intNewTotal + intGrades.Length - 1 
      intNewCount += 1 
     Loop 

     dblNewAverage = intNewTotal/3 

數學很接近但並不完全。對於100,100,80和100的分數，我得到以下結果：所有4的平均值= 95，最低分數下降的平均值= 101.新的平均值總是比它應該高一個。我能做些什麼來解決這個問題？我真的很想理解，所以如果它再次發生，我可以解決這個問題。謝謝！

Answer 1

這可能是家庭作業，在這種情況下，你不會明白無論如何。但如果你真正想學習一親會怎麼做，代碼看起來會像這樣：

Dim Grades As New List(Of Integer) From {CInt(txtGrade1.Text), CInt(txtGrade2.Text), CInt(txtGrade3.Text), CInt(txtGrade4.Text)} 

Dim Total As Integer = Grades.Sum() 
Dim Average As Double = Grades.Average()  'holds the average of all 4 grades 
Dim Lowest As Integer = Grades.Min()  'holds the lowest score 
Dim NewAverage As Double = CDbl(Total - Lowest)/(Grades.Count - 1) 

拖放您的變量名傻類型的前綴。在Option Strict是默認設置之前，他們曾經很流行並且很有意義，但現在甚至微軟自己的風格指南都建議不要這樣做。

Answer 2

的問題是這行代碼：

intNewTotal = intNewTotal + intGrades.Length - 1 

取而代之的將等級值，你加intGrades數組的長度，直到到達做，當條件：intNewTotal <= (intTotal - intLowest)

我明白你的問題是爲了學術目的，所以如果你真的需要使用Do While循環來計算平均值，我會以這種方式使用它（未經測試）：

Dim index As Int = 0 
Do While index <= intMAX_SUBSCRIPT 

    If (intGrades(index) <= intLowest) Then 
    intNewTotal += intGrades(index) 
    intNewCount += 1  
    End if 

    index += 1 

Loop 

dblNewAverage = intNewTotal/intNewCount 

編輯

刪除最低年級可能會被解釋爲2種不同的方式。如果您的值爲80,80,100,110，則您可能只想放置其中一個值，或者兩者都是。我上面的代碼正在放棄他們兩個。如果要刪除只是其中之一，那麼你應該開始索引設置爲1，則忽略第一項，刪除if條件：

Dim index As Int = 1 
Do While index <= intMAX_SUBSCRIPT 
    intNewTotal += intGrades(index) 
    index += 1 
Loop 

dblNewAverage = intNewTotal/(intGrades.Length - 1) 

Answer 3

Dim j As New List(Of Int32) 
    Dim sum As Int32 = 0 
    For i = 1 To 4 '4 number of textboxes 
     j.Add(CType(Controls.Item("txtGrade" + i.ToString), TextBox).Text) 
     sum += Val(CType(Controls.Item("txtGrade" + i.ToString), TextBox).Text) 
    Next 
    j.Sort() 
    Dim intLowest As Int32 = j(0) 
    Dim avg As Int32 = sum/j.Count