Visual Basic中如何在类内声明固定长度的数组属性？

错误原因解析 #

你遇到的错误翻译为：

错误BC36759：自动实现的属性不能包含参数

原代码的问题在于：

• 自动实现属性（Public Property ... As ...这种简写形式）不允许带参数；
• 数组的声明语法不符合VB规范，不能直接在属性名后用(width*height)指定长度。

解决方案 #

根据width和height是否为固定值，提供两种实现方式：

1. 当width和height是固定常量时 #

Public Class Board
    ' 定义固定的宽高常量
    Private Const BoardWidth As Integer = 2
    Private Const BoardHeight As Integer = 4
    
    ' 私有字段：初始化数组为指定长度，所有元素默认值为0
    Private _squares As Integer() = New Integer(BoardWidth * BoardHeight - 1) {}
    
    ' 公开属性
    Public Property squares() As Integer()
        Get
            Return _squares
        End Get
        Set(value As Integer())
            ' 可选：校验赋值的数组长度是否符合要求
            If value.Length <> BoardWidth * BoardHeight Then
                Throw New ArgumentException($"数组长度必须为{BoardWidth * BoardHeight}")
            End If
            _squares = value
        End Set
    End Property
End Class

2. 当width和height需要实例化时传入 #

Public Class Board
    Private ReadOnly _width As Integer
    Private ReadOnly _height As Integer
    Private _squares As Integer()
    
    ' 构造函数：传入宽高并初始化数组
    Public Sub New(boardWidth As Integer, boardHeight As Integer)
        _width = boardWidth
        _height = boardHeight
        ' 初始化数组，所有元素默认值为0
        _squares = New Integer(boardWidth * boardHeight - 1) {}
    End Sub
    
    Public Property squares() As Integer()
        Get
            Return _squares
        End Get
        Set(value As Integer())
            If value.Length <> _width * _height Then
                Throw New ArgumentException($"数组长度必须为{_width * _height}")
            End If
            _squares = value
        End Set
    End Property
End Class

3. 只读属性（仅允许修改数组元素，不允许替换整个数组） #

如果不需要外部替换整个数组，仅允许修改单个元素，可以将属性设为只读：

Public Class Board
    Private Const BoardWidth As Integer = 2
    Private Const BoardHeight As Integer = 4
    ' 只读私有字段，初始化后无法替换数组引用
    Private ReadOnly _squares As Integer() = New Integer(BoardWidth * BoardHeight - 1) {}
    
    Public ReadOnly Property squares() As Integer()
        Get
            Return _squares
        End Get
    End Property
End Class

说明：VB中声明New Integer(n){}时，数组的索引范围是0到n，总元素个数为n+1。因此要创建长度为width*height的数组，需使用New Integer(width*height -1){}，且值类型Integer的默认值为0，无需额外赋值。

内容的提问来源于stack exchange，提问作者pfzhou