比较两个数组并将唯一元素从第二个数组复制到第一个数组VB.NET

Question

我有两个数组：TempSubject()，它携带一个科目列表，和friRoutine()，它指示何时教授科目。

我需要强制执行一项规则，即任何特定科目都不能在特定日期教授两次。我有一个名为DetectDuplicate(friRoutine, Tempsubject(i)) 的函数，它检查friRoutine() 和TempSubject() 并查找friRoutine 是否已经包含特定主题。如果否，则将该唯一主题添加到 friRoutine。否则继续循环下一个主题。我的代码如下提供-

Dim TempSubject() As String = {"Maths","English","Sanskrit","Sanskrit","Urdu","Urdu","Urdu","French","French","French","Physical Education","Physical Education","Game","Game", "Science"}

dim c4 as integer = 0
dim limitcounter = 0
dim friRoutine() as string
reedim friRoutine(6)

While c4 < TempSubject.Length
    If DetectDuplicate(friRoutine, TempSubject(c4)) = False And limitcounter4 < 7 Then
        friRoutine(limitcounter4) = TempSubject(c4)
        'MessageBox.Show(c1 & ": " & limitcounter1 & ": " & tueRoutine(limitcounter1))
        Debug.WriteLine("Friday: " & c4 & ": " & limitcounter4 & ": " & friRoutine(limitcounter4))
        TempSubject.RemoveAt(c4)
        limitcounter4 = limitcounter4 + 1
    End If
    c4 = c4 + 1
End While


Private Function DetectDuplicate(ByVal arr As Array, ByVal str As String) As Boolean
    Dim numcount As Integer = 0
    For numcount = 0 To arr.Length - 1
        If arr(numcount) = str Then
            Return True
        End If
    Next
    Return False
End Function

输出应该是

friRoutine = Math, english, sanskrit, Urdu, French, Physical education, game

但不幸的是，缺少英语。 输出是：

friRoutine = Math, sanskrit, Urdu, French, Physical education, game, science

我害怕使用我的代码，因为它可能会在任何时候破坏整个过程。 我认为问题在于函数 DetectDuplicate()

编辑（来自评论）

我必须删除使用过的元素。我最初的课程将有 42 个科目和 6 天。每天7节。例如，如果我在星期一选择了 7 个独特的科目，那么在接下来的 6 天里，我必须在剩下的 5 天里调整 35 个科目。

Answer 1

我要做的第一件事是将数组转换为通用列表。所以这个：

Dim TempSubject() As String = {"Maths","English","Sanskrit","Sanskrit","Urdu","Urdu","Urdu","French","French","French","Physical Education","Physical Education","Game","Game", "Science"}
Dim friRoutine() As String

变成这样：

Dim TempSubject As New List(Of String) From {"Maths","English","Sanskrit","Sanskrit","Urdu","Urdu","Urdu","French","French","French","Physical Education","Physical Education","Game","Game", "Science"}
Dim friRoutine As New List(Of String)(6)

您可以通过索引访问这些列表中的项目，就像使用数组一样，但是现在执行诸如添加或删除条目之类的操作变得好多了。 至少，我会为friRoutine 集合这样做；在此代码中使用TempSubject 的方式对数组进行了一些论证，但即使在那里，数据也可能来自某个地方，可以证明 List(Of String) 是合理的。

完成后，您可以大大简化代码：

friRoutine.AddRange(TempSubject)
friRoutine = friRoutine.Distinct().Take(7).ToList()

或者，显示整个示例：

Dim TempSubject = {"Maths","English","Sanskrit","Sanskrit","Urdu","Urdu","Urdu","French","French","French","Physical Education","Physical Education","Game","Game", "Science"}

Dim friRoutine As New List(Of String)(TempSubject.Distinct().Take(7))
For i As Integer = 0 to friRoutine.Count - 1
    Debug.WriteLine($"Friday: {i} : {friRoutine(i)}")
Next 

现在我们看到friRoutine 的数据可以通过一行代码计算出来，有人想知道我们是否真的需要单独的集合。

至于原始代码，最大的问题是这一行：

TempSubject.RemoveAt(c4)

这修改了集合，同时仍在循环中。一切都会向前移动，导致一些项目被跳过。

Answer 2

只需使用Enumerable.Distinct<T>()

Dim TempSubject = {"Maths","English","Sanskrit","Sanskrit","Urdu","Urdu","Urdu","French","French","French","Physical Education","Physical Education","Game","Game", "Science"}

Dim friRoutine = TempSubject.Distinct().ToArray()

如果你想要一个列表输出，那么它很简单

Dim friRoutine = TempSubject.Distinct().ToList()

由于数组和列表都是可枚举的，TempSubject 可以是数组或列表。