Question

在我的VB学校项目中，我们正在做区域计算器。这是我目前的计划。当我在“输入侧宽度”（第45行）处设置断点时，它表示输入为0，但根据我标记为“GetVal”的函数，它应该是readline（）。其余的功能部件没有使用GetVal，因为我想让它首先在正方形上工作。

Imports System.Console
Module Module1
    Private Function SquareArea(ByVal Length As Single, ByVal Width As Single) As Single
        Return Length * Width
    End Function
    Private Function CircleArea(ByVal Radius As Single) As Single
        Return 3.14159 * (Radius * Radius)
    End Function
    Private Function TriArea(ByVal Base As Single, ByVal Height As Single) As Single
        Return (Base * Height) / 2
    End Function
    Private Function GetVal(ByVal Input As Single) As Single
        Input = ReadLine()
        Return Input
    End Function

    Sub Main()
        Dim Length, Width, answer, Radius, Base, Height, Input As Single
        Dim Validinput As Integer
        Dim Choice As String
        Do
            WriteLine("Press the nunmpad for the area you want to find")
            WriteLine("1 for Rectangle/Square, 2 for Circle, 3 for Triangle")
            Do
                Validinput = True
                Choice = ReadKey(True).Key
                If Choice <> ConsoleKey.NumPad1 And Choice <> ConsoleKey.NumPad2 And Choice <> ConsoleKey.NumPad3 Then Validinput = False
            Loop Until Validinput
            'Square/Rectangle'
            If Choice = ConsoleKey.NumPad1 Then
                WriteLine("Enter Side Length")
                Do
                    Validinput = True
                    Try
                        GetVal(Input = Length)
                        Input = Length
                    Catch ex As Exception
                        WriteLine("Error, Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput = True

                WriteLine("Enter Side Width")
                Do
                    Validinput = True
                    Try
                        GetVal(Input = Width)
                        Input = Width
                    Catch ex As Exception
                        WriteLine("Please enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput = True
                WriteLine(SquareArea(Length, Width))
            End If
            'Circle'
            If Choice = ConsoleKey.NumPad2 Then
                WriteLine("Enter Radius")
                Do
                    Validinput = True
                    Try
                        Radius = ReadLine()
                        WriteLine(CircleArea(Radius))
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput = True
            End If
            'Triangle'
            If Choice = ConsoleKey.NumPad3 Then
                WriteLine("Enter Base Length")
                Do
                    Validinput = True
                    Try
                        Base = ReadLine()
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput

                WriteLine("Enter Height Size")
                Do
                    Validinput = True
                    Try
                        Height = ReadLine()
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput
                WriteLine(TriArea(Base, Height))
            End If
        WriteLine("")


        Loop

    End Sub

End Module

------------编辑------------------

如果有人遇到同样的问题，我的最终工作代码。我知道它不漂亮，但确实如此：

Imports System.Console
Module Module1
Private Function SquareArea(ByVal Length As Single, ByVal Width As Single) As Single
    Return Length * Width
End Function
Private Function CircleArea(ByVal Radius As Single) As Single
    Return Math.PI * (Radius * Radius)
End Function
Private Function TriArea(ByVal Base As Single, ByVal Height As Single) As Single
    Return (Base * Height) / 2
End Function
Private Function GetVal(ByVal Input As Single) As Short
    Dim ValueOK As Boolean
    Do
        ValueOK = True
        Try
            Input = Readline()
        Catch ex As Exception
            ValueOK = False
            WriteLine("Error, please enter a number")
        End Try
    Loop Until ValueOK
    Return Input
End Function

Sub Main()
    Dim Length, Width, Radius, PI, Base, Height, Input As Short
    Dim Validinput As Integer
    Dim Choice As String
    Do
        WriteLine("Press the nunmpad for the area you want to find")
        WriteLine("1 for Rectangle/Square, 2 for Circle, 3 for Triangle")
        Do
            Validinput = True
            Choice = ReadKey(True).Key
            If Choice <> ConsoleKey.NumPad1 And Choice <> ConsoleKey.NumPad2 And Choice <> ConsoleKey.NumPad3 Then Validinput = False
        Loop Until Validinput
        'Square/Rectangle'
        If Choice = ConsoleKey.NumPad1 Then
            WriteLine("Enter Side Length")
            Validinput = True
            Length = GetVal(123456.0)
            Input = Length

            WriteLine("Enter Side Width")
            Validinput = True
            Width = GetVal(123456.0)
            Input = Width

            WriteLine(SquareArea(Length, Width))
        End If
        'Circle'
        If Choice = ConsoleKey.NumPad2 Then
            WriteLine("Enter Radius")
            Validinput = True
            Radius = GetVal(123456.0)
            Input = Radius

            WriteLine(CircleArea(Radius))

        End If
        'Triangle'
        If Choice = ConsoleKey.NumPad3 Then
            WriteLine("Enter Base Length")
            Validinput = True
            Base = GetVal(123456.0)
            Input = Base


            WriteLine("Enter Height Size")
            Validinput = True
            Height = GetVal(123456.0)
            Input = Height
    WriteLine(TriArea(Base, Height))
        End If
        WriteLine("")
    Loop
End Sub

End Module

Answer 1

首先，如果你有Option Strict On，这甚至都不会编译。你的部分问题是：

GetVal(Input = Length)

在这里，您基本上是在调用GetVal(True)或GetVal(False)，因为Input = Length是一个比较，并且评估为真或假。

此外，您正在调用一个返回值的Function，但对返回值不执行任何操作。这里有2个选项：

将您的功能更改为ByRef而不是ByVal，这样您就可以覆盖传入的变量。
将GetVal(Input = Length)等更改为Length = GetVal(123456.0)。事实上，你编写函数的方式，你传递给GetVal的数字甚至都不重要，因为它会立即被覆盖在函数内部。你可以简单地改变GetVal根本不接受任何数字，这没有任何区别。

解决方案＃2是更好的解决方案，也是正确的方法。

你需要这样的东西：

Option Strict On

Imports System.Console

Module Module1

    Private Function SquareArea(ByVal Length As Single, ByVal Width As Single) As Single
        Return (Length * Width)
    End Function

    Private Function CircleArea(ByVal Radius As Single) As Single
        Return (Math.PI * (Radius * Radius))
    End Function

    Private Function TriArea(ByVal Base As Single, ByVal Height As Single) As Single
        Return (Base * Height) / 2.0
    End Function

    Private Function GetVal() As Single
        Dim userInput As String = ReadLine()
            Return Convert.ToSingle(userInput)
        End Try
    End Function

    Sub Main()
        Dim Length As Single
        Dim Width As Single
        Dim answer As Single
        Dim Radius As Single
        Dim Base As Single
        Dim Height As Single
        Dim Validinput As Integer

        Dim Choice As String
        Do
            WriteLine("Press the nunmpad for the area you want to find")
            WriteLine("1 for Rectangle/Square, 2 for Circle, 3 for Triangle")
            Do
                Validinput = True
                Choice = ReadKey(True).Key
                If Choice <> ConsoleKey.NumPad1 And Choice <> ConsoleKey.NumPad2 And Choice <> ConsoleKey.NumPad3 Then Validinput = False
            Loop Until Validinput
            'Square/Rectangle'
            If Choice = ConsoleKey.NumPad1 Then
                WriteLine("Enter Side Length")
                Do
                    Validinput = True
                    Try
                        Length = GetVal()
                    Catch ex As Exception
                        WriteLine("Error, Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput

                WriteLine("Enter Side Width")
                Do
                    Validinput = True
                    Try
                        Width = GetVal()
                    Catch ex As Exception
                        WriteLine("Please enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput
                WriteLine(SquareArea(Length, Width))
            End If
            'Circle'
            If Choice = ConsoleKey.NumPad2 Then
                WriteLine("Enter Radius")
                Do
                    Validinput = True
                    Try
                        Radius = GetVal()
                        WriteLine(CircleArea(Radius))
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput
            End If
            'Triangle'
            If Choice = ConsoleKey.NumPad3 Then
                WriteLine("Enter Base Length")
                Do
                    Validinput = True
                    Try
                        Base = GetVal()
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput

                WriteLine("Enter Height Size")
                Do
                    Validinput = True
                    Try
                        Height = GetVal()
                    Catch ex As Exception
                        WriteLine("Please Enter a number")
                        Validinput = False
                    End Try
                Loop Until Validinput
                WriteLine(TriArea(Base, Height))
            End If
        WriteLine("")

        Loop

    End Sub

End Module

此外，这是使用Select Case语句而不是多个If语句的情况。

Visual Basic中的函数和获取值

1 个答案: