VB.net 表达式不产生值错误

Question

我是 vb.net 的新手，一般编程很抱歉，如果这是一个基本错误，但我试图在 vb.net 中制作 ax 和 o 的游戏，它一直说我的 CheckForWin 不会产生一个对我来说意义为零的值，当我查了一下，唯一的问题是关于将不同的代码转换为 vb.net 并且没有提到我遇到的问题这是我的代码：Public Class Form1

Dim Board(9) As String
Dim Player1 As String = "X"
Dim Player2 As String = "O"

Public Property X As String

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

End Sub

Private Sub ResetBoard()
    Do
        If CheckForWin() = True Then
            Board(0) = 0
            Board(1) = 0
            Board(2) = 0
            Board(3) = 0
            Board(4) = 0
            Board(5) = 0
            Board(6) = 0
            Board(7) = 0
            Board(8) = 0

        End If
    Loop Until Board(0) = 0
    Board(1) = 0
    Board(2) = 0
    Board(3) = 0
    Board(4) = 0
    Board(5) = 0
    Board(6) = 0
    Board(7) = 0
    Board(8) = 0
End Sub

Private Sub CheckForWin()
    If "0""3""6" = X Then
        ResetBoard()
    ElseIf "1""4""7" = X Then
        ResetBoard()
    ElseIf "2""5""8" = X Then
        ResetBoard()
    ElseIf "0""1""2" = X Then
        ResetBoard()
    ElseIf "3""4""5" = X Then
        ResetBoard()
    ElseIf "6""7""8" = X Then
        ResetBoard()
    ElseIf "0""4""8" = X Then
        ResetBoard()
    ElseIf "2""4""6" = X Then
        ResetBoard()
    ElseIf "0""3""6" = 0 Then
        ResetBoard()
    ElseIf "1""4""7" = 0 Then
        ResetBoard()
    ElseIf "2""5""8" = 0 Then
        ResetBoard()
    ElseIf "0""1""2" = 0 Then
        ResetBoard()
    ElseIf "3""4""5" = 0 Then
        ResetBoard()
    ElseIf "6""7""8" = 0 Then
        ResetBoard()
    ElseIf "0""4""8" = 0 Then
        ResetBoard()
    ElseIf "2""4""6" = 0 Then
        ResetBoard()
    End If
End Sub

End Class

问题出在这行代码中： If CheckForWin() = True Then

Answer 1

这行代码：

If CheckForWin() = True Then
    ...
End If

这将设置条件检查以查看CheckForWin方法的结果是否为真。 问题是该方法是一个 Sub 例程，而不是 Function。

Function 表示一个返回值的代码块，而 Sub 也表示一个代码块，但它不返回值。

更重要的是，它看起来好像您陷入了无限循环。 ResetBoard调用CheckForWin ，后者调用ResetBoard ，后者调用...等等。

最简单的做法是：

1. 将CheckForWin转换为 Function
2. 停止在CheckForWin方法中调用ResetBoard
3. 当ResetBoard方法中的任何条件检查为 True 时返回 True

这是一个例子：

Private Sub ResetBoard()
    ' check if there is a winner, if not then stop execution of the method early
    Dim isWin = CheckForWin()
    If (Not isWin) Then
        Return
    End If

    For index = 1 To 8
        Board(index) = 0
    Next
End Sub

Private Function CheckForWin() As Boolean
    Dim winningPatterns = {
        "0""3""6",
        "1""4""7",
        "2""5""8",
        ' etc...
    }
    Dim doAnyMatch = winningPatterns.Contains(X)
    Return doAnyMatch
End Function