Question

家庭作业任务是简单地允许用户输入值（字符串）“FD__”并将其与已知输入列表匹配并返回true / false。已经定义了ID并且它运行良好，当我键入一个定义为Products(2)的ID为“FD3”时，它将返回true，如果未定义该值，它将不仅没有给出结果但是崩溃了程序，所以总的来说，真正的工作，但错误的不是。任何信息都可能有所帮助。

设计：http://i.imgur.com/bJnFAMX.png

Public Class Form1

    'variables
    Dim Products(9) As String
    Dim Entered As String
    Dim Found As Boolean

    Public Sub btnFind_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFind.Click
        'Product variable array elements
        Products(0) = "FD1"
        Products(1) = "FD2"
        Products(2) = "FD3"
        Products(3) = "FD4"
        Products(4) = "FD5"
        Products(5) = "FD6"
        Products(6) = "FD7"
        Products(7) = "FD8"
        Products(8) = "FD9"
        Products(9) = "FD10"
        'process
        Entered = txtFind.Text 'define entered value as variable
        Found = FindNumber() 'sub function
        If Found Then
            lblResult.Text = Found 'change the results
        End If
    End Sub

    Public Function FindNumber()
        'If true statements
        Do While (Found = False)
            If Entered = Products(0) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(1) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(2) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(3) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(4) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(5) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(6) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(7) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(8) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            ElseIf Entered = Products(9) Then
                Found = True
                lblResult.ForeColor = Color.LawnGreen
            Else 'keeps crashing
                Found = False
                lblResult.ForeColor = Color.Red
            End If
        Loop
        Return Found
    End Function
End Class

Answer 1

你实际上可以通过很多更少的代码来实现这一点......我会继续前进并在此时做一些批评。

'1. Functions should have return types
'2. You should pass the function what it needs to do its job 
Public Function FindNumber(numberEntered As String) As Boolean
   'Rather than evaluating if a condition is true or false, and then returning
   'true or false, you can just directly return the condition.
   Return Products.Contains(numberEntered)
End Function

然后在你的主程序中：

'This doesn't need to be a class level variable
Dim entered = txtFind.Text
'Local variables should be lowercase
Dim found = FindNumber(entered)
If found Then
  'With Option Strict you can't assign a Boolean to a String...
  'but you can do .ToString() instead
  lblResult.Text = found.ToString()
  'And this was really dependent on the result of the function...
  'Also it has nothing to do with finding the number...
  lblResult.ForeColor = Color.LawnGreen
Else
  lblResult.ForeColor = Color.Red
End If

它看起来要长得多，但请注意这些评论，我保证这将是一个更简单（更短）的程序。

Answer 2

您可以使用.contains函数优化整个代码，这个简单的用法如下：

如果是mylist.contains（＆＃34; sometext＆＃34;）那么＆＃39;将forecolor更改为绿色其他＆＃39;将forecolor更改为红色结束如果

这可以缓解您的问题。

验证数组输入时的无限循环

2 个答案: