什么是Visual Basic中的"属性字符只读",我该如何解决？

Question

我的目标是这样做:将文件中的数据读入数组,加载列表框,计算每个学生的平均值并确定字母等级,并计算课程平均值:

我声明的变量(全局):

昏暗项目,midterm,hw1,hw2,final,count,average As Integer

Dim letterGrade, lastName, firstName As String
Dim classAverage As Double

---

我的代码:

Dim array1 As String()= New String(6){}

    Dim streamreader1 As StreamReader = File.OpenText("grades.csv")
    count = 0
    classAverage = 0
    Do While (streamreader1.Peek() <> -1)
        array1 = Strings.Split(streamreader1.ReadLine(), ",", -1)
        firstName(count) = array1(0)
        lastName(count) = array1(1)
        lstNames.Items.Add(lastName(count) & ", " & firstName(count))
        hw1(count) = Convert.ToString(array1(2))
        hw2(count) = Convert.ToString(array1(3))
        project(count) = Convert.ToString(array1(4))
        midterm(count) = Convert.ToString(array1(5))
        final(count) = Convert.ToString(array1(6))
        average(count) = Math.Round(Math.Truncate((((((hw1(count) + hw2(count)) + (2 * project(count))) + (4 * (midterm(count) + final(count)))) / 12) + 0.5)))
        classAverage = (classAverage + ((((hw1(count) + hw2(count)) + (2 * project(count))) + (4 * (midterm(count) + final(count)))) / 12))
        Dim num1 As Integer = average(count)
        If (num1 >= 93) Then
            letterGrade(count) = "A"
        ElseIf (num1 >= 90) Then
            letterGrade(count) = "A-"
        ElseIf (num1 >= 87) Then
            letterGrade(count) = "B+"
        ElseIf (num1 >= 83) Then
            letterGrade(count) = "B"
        ElseIf (num1 >= 80) Then
            letterGrade(count) = "B-"
        ElseIf (num1 >= 77) Then
            letterGrade(count) = "C+"
        ElseIf (num1 >= 73) Then
            letterGrade(count) = "C"
        ElseIf (num1 >= 70) Then
            letterGrade(count) = "C-"
        ElseIf (num1 >= 67) Then
            letterGrade(count) = "D+"
        ElseIf (num1 >= 63) Then
            letterGrade(count) = "D"
        ElseIf (num1 >= 60) Then
            letterGrade(count) = "D"
        Else
            letterGrade(count) = "E"
        End If
        count = (count + 1)

    Loop
    classAverage = (classAverage / count)
    lstNames.SelectedIndex = 0
    PopulateLabels(0)
    streamreader1.Close()

Answer 1

看起来像是letterGrade一个String字符串数组.您需要将其正确声明为数组.

编辑完成后......

我建议创建一个Student包含文本文件中的值的类.它还包含针对对象本身执行CalculateAverage()和CalculateLetterGrade()执行的方法.然后将每行从文本文件转储到一个Student对象中,并添加到一个List(Of Student).获得此列表后,您可以遍历一个很好的简单对象列表来计算类平均值.

像这样的东西:

Public Class Student
    Public FirstName As String
    Public LastName As String
    Public Project As Integer
    ...
    Public Final As Integer

    Public Function CalculateAverage() As Integer
        ... ' Your calculation function
    End Function

    Public Function CalculateLetterGrade() As String
        ... ' Your calculation function
    End Function
End Class

Dim students As New List(Of Student)

'Inside your loop:
    Dim student As New Student()
    student.Project = Convert.ToString(array1(4))
    ... ' etc.
    students.Add(student)

此时,您将拥有一个简单的学生集合,您可以循环浏览它们,计算您的课程平均值或您需要的任何其他内容.