在vb中有更快或更短的方法吗？

Question

我有一个应用程序可以检查用户输入的内容是否在从A到F的文本范围内，我的代码可以正常工作，但我只是认为应该有一种更短的方法，可能在一行中？

这是代码：

Private Sub ResultButton_Click(sender As Object, e As EventArgs) Handles ResultButton.Click

        Dim Range_A As Integer, Range_B As Integer, Range_C As Integer,
            Range_D As Integer, Range_E As Integer, Range_F As Integer, Range_Check As Integer

        Range_A = Integer.Parse(inputTextBox.Text)
        Range_B = Integer.Parse(inputTextBox.Text)
        Range_C = Integer.Parse(inputTextBox.Text)
        Range_D = Integer.Parse(inputTextBox.Text)
        Range_E = Integer.Parse(inputTextBox.Text)
        Range_F = Integer.Parse(inputTextBox.Text)

        Range_Check = Integer.Parse(inputTextBox.Text)

        If Range_Check >= 101 Or Range_Check < 0 Then

            MessageBox.Show(" Only values within 0 and 100 are allowed, please type a number within this range.")

        End If


        If Range_F >= 0 And Range_F <= 39 Then

            MessageBox.Show(" " & Range_F & " is within the F Range")
            Exit Sub

        End If

        If Range_E >= 40 And Range_E <= 44 Then

            MessageBox.Show(" " & Range_E & " is within the E Range")
            Exit Sub

        End If

        If Range_D >= 45 And Range_D <= 49 Then

            MessageBox.Show(" " & Range_D & " is within the D Range")
            Exit Sub

        End If

        If Range_C >= 50 And Range_C <= 59 Then

            MessageBox.Show(" " & Range_C & " is within the C Range")
            Exit Sub

        End If

        If Range_B >= 60 And Range_B <= 69 Then

            MessageBox.Show(" " & Range_B & " is within the B Range")
            Exit Sub
        End If

        If Range_A >= 70 And Range_A <= 100 Then

            MessageBox.Show(" " & Range_A & " is within the A Range")
            Exit Sub

        End If


    End Sub

我要重复相同的Integer.Parse语句，这在我上次检查时并不总是一个好主意，请问如何优化这些代码行？

Answer 1

    Select Case Integer.Parse(inputTextBox.Text)
        Case 70 To 100
            MessageBox.Show("Your Grade is A")
        Case Is > 60
            MessageBox.Show("Your Grade is B")
        Case Is > 50
            MessageBox.Show("Your Grade is C")
        Case Is > 45
            MessageBox.Show("Your Grade is D")
        Case Is > 40
            MessageBox.Show("Your Grade is E")
        Case Is > 0
            MessageBox.Show("Your Grade is F")
        Case Else
            MessageBox.Show("Only values within 0 and 100 are allowed, please type a number within this range.")
    End Select

Answer 2

  Dim range As String = ""
  If Not Integer.TryParse(inputTextBox.Text, theValue) Then
        MessageBox.Show("Enter only numerals, please")
        Exit Sub
  End if

  ' if integer,.tryparse is true then theValue will have the result

  Select Case theValue
      Case Is > 100, Is < 1
          ' do err msg

      Case 0 to 39
         range = "A"

      Case 40 To 50
         range = "B"

     ' etc...or:

      Case 41 to 44
            MessageBox.Show(" " & inputTextBox.Text & " is within the E Range")
  End Select

2个变量，1个解析或仅求值，并像上一个一样显示消息。 将这些保存到变量的主要原因是，如果您需要其他结果

Answer 3

您只需解析一次输入文本框，然后用普通的Range替换Range_A，Range_B，Range_Check等的每个实例，因此：

Dim Range As Integer

Range = Integer.Parse(inputTextBox.Text)

If Range >= 101 Or Range  < 0 Then
        MessageBox.Show(" Only values within 0 and 100 are allowed, please type a number within this range.")
End If

If Range >= 0 And Range <= 39 Then
        MessageBox.Show(" " & Range  & " is within the F Range")
End If

...等等所有检查。 为这些名称使用单独的名称不会执行任何操作。