How Can I Efficiently Compare Two List Objects for Content Equality in C#?

Compare the contents of List objects in C# to see if they are equal

When comparing two List objects, you often need to determine whether they contain the same elements, regardless of the order of the elements. This begs the question: does C# provide a built-in function for this type of comparison?

If element order doesn't matter, sorting both lists before comparing is a straightforward approach. This can be achieved using the following code:

<code class="language-csharp">Enumerable.SequenceEqual(list1.OrderBy(t => t), list2.OrderBy(t => t))</code>

Alternatively, to improve performance and be compatible with types that implement IEquatable but not IComparable, you can use the following method:

<code class="language-csharp">public static bool ScrambledEquals<T>(IEnumerable<T> list1, IEnumerable<T> list2)
{
    var cnt = new Dictionary<T, int>();

    foreach (T s in list1)
    {
        if (cnt.ContainsKey(s))
        {
            cnt[s]++;
        }
        else
        {
            cnt.Add(s, 1);
        }
    }

    foreach (T s in list2)
    {
        if (cnt.ContainsKey(s))
        {
            cnt[s]--;
        }
        else
        {
            return false;
        }
    }

    return cnt.Values.All(c => c == 0);
}</code>

If the data type used as the key does not support equality comparisons by default, you can use another version of the above function that takes an equality comparator as a parameter:

<code class="language-csharp">public static bool ScrambledEquals<T>(IEnumerable<T> list1, IEnumerable<T> list2, IEqualityComparer<T> comparer)
{
    var cnt = new Dictionary<T, int>(comparer);

    //其余代码保持不变
}</code>

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