Question

您好我正在尝试使用在文本框txtRECORD中输入的按钮btnRECORD将新成绩添加到文本文件中。我正在使用按钮btnDISPLAY来计算成绩的平均值和高于平均水平的成绩数，并将其显示在列表框中。但我似乎无法使用btnRECORD为文本文件添加新的成绩。（文本文件为空）

  Public Class frmGRADES
Dim temp() As String = IO.File.ReadAllLines("Exam.txt")
Dim grades(temp.Length - 1) As Double
Dim average As Double
Dim aboveAverage As Integer

Function avg(ByVal average As Double, ByVal aboveAverage As Integer)//function for average
    For i As Double = 0 To grades.Length - 1
        If grades(i) > average Then
            aboveAverage = aboveAverage + 1
        End If
    Next
    Return aboveAverage
End Function

Private Sub btnRECORD_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRECORD.Click
    ReDim Preserve grades(temp.Length - 1)
    grades(temp.Length - 1) = CDbl(txtRECORD.Text)
    IO.File.WriteAllLines("Exam.txt", grades) //write grades to textfile
    aboveAverage = 0
End Sub

Private Sub btnDISPLAY_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDISPLAY.Click
    lstRESULTS.Items.Clear()
    For i As Integer = 0 To grades.Length - 1
        grades(i) = CDbl(temp(i))
    Next
    average = grades.Average
    lstRESULTS.Items.Add("The Average Score is: " & average)
    aboveAverage = avg(average, aboveAverage)


    lstRESULTS.Items.Add("Number of Grades above average is: " & aboveAverage)
    aboveAverage = 0
End Sub
End Class

Answer 1

哎呀你的C＃正在显示:)。 VB中的注释用'

表示

您的主要问题似乎是将一个double数组转换为字符串。在WriteAllLines方法中。这样的事情会更好：

    IO.File.WriteAllLines("Exam.txt", (From d In grades
                                             Let str As String = d.ToString
                                             Select str).ToArray)

我注意到的另一件事是，数组索引是整数，但是你的一个for循环是用double声明的。

要使用函数的返回类型，您应该显式声明该类型，以便编译器可以识别它。

 Function avg(ByVal average As Double, ByVal aboveAverage As Integer) As Integer

在vb.net中为文本文件添加成绩

1 个答案: