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如何从组合框中的值中删除无效的强制转换表达式以适合中的方程式examgrade？

我试图通过在 MSDN 等上查找它来解决它，但无法弄清楚。我尝试使用Examgrade = ().ToString，但没有奏效。

希望你们能指出我正确的方向。仅供参考，这是我的第一个真正的程序，我在 C# 中成功制作过一次，但删除了源文件，所以这是 Visual Basic，而且很容易做到这一点。

星号标记问题行

Public Class Calculator
Dim quarter3 As Integer
Dim quarter4 As Integer
Dim desiredgrade As String
Dim examgrade As String

 Private Sub Button1_Click(ByVal sender As System.Object, _
 ByVal e As System.EventArgs) Handles Button1.Click
    quarter3 = TextBox1.Text
    quarter4 = TextBox2.Text
    desiredgrade = ComboBox1.Text
    ****examgrade = ((desiredgrade - (quarter3 * 0.4) - _
    (quarter4 * 0.4)) / 0.2)****

    If examgrade > 100 Then
        Label5.Text = examgrade + " YOLO"
    ElseIf examgrade < 0 Then
        Label5.Text = "Impossible"
    Else
        Label5.Text = examgrade
    End If
End Sub

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender _
As System.Object, ByVal e As System.EventArgs) Handles _
ComboBox1.SelectedIndexChanged
    Dim A As Integer
    Dim B As Integer
    Dim C As Integer
    Dim D As Integer
    A = 90
    B = 80
    C = 70
    D = 60
    ComboBox1.EndUpdate()
End Sub
End Class
4

2 回答 2

2

desiredgrade是一个字符串

examgrade = ((Double.Parse(desiredgrade) - (quarter3 * 0.4) - _
            (quarter4 * 0.4)) / 0.2).ToString()

我正在使用Double. Integer如果需要，您也可以使用。

examgrade = ((Integer.Parse(desiredgrade) - (quarter3 * 0.4) - _
            (quarter4 * 0.4)) / 0.2).ToString()
于 2012-05-29T16:44:50.973 回答
1

Unless there's a specific reason for having examgrade as a String, try the following:

Dim examgrade as Integer

examgrade = ((CInt(desiredgrade) - (quarter3 * 0.4) - _
(quarter4 * 0.4)) / 0.2)

VB will automatically convert examgrade to a String when you assign it to your label.

于 2012-05-29T16:49:54.377 回答