VB.NET：检查列表项是否相等并且具有相同的计数

问题描述

如何检测两个给定列表的项目是否相等？

How can I detect whether the items of two given lists are equal?

Dim list1 As New List(Of Integer)
list1.AddRange({1, 2, 3})

Dim list2 As New List(Of Integer)
list2.AddRange({3, 2, 1})

如果我使用 SequenceEqual code> False ，因为项目的顺序不同。

If I compare them using SequenceEqual I get False because the order of the items is not the same. How can I compare them without sorting them first, though?

编辑：请注意，这应该尊重重复的，例如 {1，2，3，1} 与 {1，2，3}不一样 $ c> 1 在第一个列表中出现两次。）

Please take into account that this should respect duplicates, for example {1, 2, 3, 1} is not the same as {1, 2, 3} (item 1 occurs two times in the first list).

推荐答案

<System.Runtime.CompilerServices.Extension()> _
Function AreItemsEqual(Of T)(col1 As IEnumerable(Of T), col2 As IEnumerable(Of T)) As Boolean
    ' performance checks
    If col1 Is col2 Then Return True
    If col1 Is Nothing OrElse col2 Is Nothing Then Return False
    If col1.Count <> col2.Count Then Return False
    ' compare their elements
    Dim o1 As IEnumerable(Of T) = col1.OrderBy(Function(i) i)
    Dim o2 As IEnumerable(Of T) = col2.OrderBy(Function(i) i)
    Return o1.SequenceEqual(o2)
End Function

b $ b

用法：

Usage:

If list1.AreItemsEqual(list2) Then
    ...

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