VB迷惑了，如果路徑

我有VB程序，用戶是使用InputBox輸入成績。無論用戶輸入什麼，都會顯示一個消息框（msgbox），指出「請輸入一個數字」。如果沒有輸入號碼，我該如何改變它才顯示這條信息？VB迷惑了，如果路徑

Option Strict Off 

Public Class Form1 

Dim totalpointsaccumultator As Object 

Private Sub exitButton_Click(sender As Object, e As EventArgs) Handles exitButton.Click 
    Me.Close() 
End Sub 

Public Sub assignButton_Click(sender As Object, e As EventArgs) Handles assignButton.Click 
    Dim inputProjectPoints, inputTestPoints As String 
    Dim grade, projectpoints, testpoints As String 
    Dim projectcounter As Integer = 1 
    Dim testcounter As Integer = 1 
    Dim isconverted As Boolean 
    Dim totalpointsaccumulator As Integer 
    Do While projectcounter < 5 
     inputProjectPoints = InputBox("Enter the points earned on project " & projectcounter, "Grade Calculator", "0") 
     inputProjectPoints = projectpoints 
     isconverted = Integer.TryParse(inputProjectPoints, CInt(projectpoints)) 
     If isconverted Then 
      totalpointsaccumultator = totalpointsaccumulator + projectpoints 
      projectcounter = projectcounter + 1 
     Else 
      MessageBox.Show("Please enter a number.", "Grade Calculator", MessageBoxButtons.OK, MessageBoxIcon.Information) 
     End If 
    Loop 

    Do While testcounter < 3 
     inputTestPoints = InputBox("Enter the points earned on test " & testcounter, "Grade Calculator", "0") 
     isconverted = Integer.TryParse(inputTestPoints, testpoints) 
     If isconverted Then 
      testcounter = testcounter + 1 
      totalpointsaccumulator = CInt(totalpointsaccumulator + testpoints) 
     Else 
      MessageBox.Show("Please enter a number.", "Grade calculator", MessageBoxButtons.OK, MessageBoxIcon.Information) 
     End If 
    Loop 

    ' assign grade 
    Select Case totalpointsaccumulator 
     Case Is >= 360 
      grade = "A" 
     Case Is >= 320 
      grade = "B" 
     Case Is >= 280 
      grade = "C" 
     Case Is >= 240 
      grade = "D" 
     Case Else 
      grade = "F" 
    End Select 
    totalpointsLabel.Text = Convert.ToString(totalpointsaccumulator) 
    gradeLabel.Text = grade 
End Sub 
End Class

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2015-11-17 Thomas Shera

我會簡化代碼，然後在這裏呈現仍然產生錯誤的最小可能版本。這不是最小的可能版本。機會很高，你會發現自己的錯誤或來自這裏的人會發現它更快。 – Trilarion

看起來像你在這裏覆蓋你的輸入：「inputProjectPoints = projectpoints」 –

Turn Option Strict ON not off！ – Plutonix

isconverted = Integer.TryParse(inputProjectPoints, CInt(projectpoints))

應該是：

isconverted = Integer.TryParse(inputProjectPoints, projectpoints)

還有：

Dim grade, projectpoints, testpoints As String

應該是：

Dim grade as String 
Dim projectpoints, testpoints As Integer

你不能PA通過嘗試轉換/轉換它來引用一個引用變量作爲不同類型，它只是返回所需類型的值（如果可能的話，考慮到您使用Integer.TryParse（），這實際上並不具有諷刺意味）更改您聲明的變量的基礎類型。

由於這個問題，你的Integer.TryParse（）總是失敗，意思是轉換總是爲false，你總是會得到消息框。

編輯：忘了補充，Plutonix是對的。設置選項嚴格開啓！

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2015-11-17 13:51:15

VB迷惑了，如果路徑

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