这里有一个扩展的方法来删除相邻的副本原位。首先调用Sort()并传入相同的ic比较器。这应该比Lasse V. Karlsen的版本更有效，后者重复调用RemoveAt(导致多次块内存移动)。

public static void RemoveAdjacentDuplicates<T>(this List<T> List, IComparer<T> Comparer)
{
    int NumUnique = 0;
    for (int i = 0; i < List.Count; i++)
        if ((i == 0) || (Comparer.Compare(List[NumUnique - 1], List[i]) != 0))
            List[NumUnique++] = List[i];
    List.RemoveRange(NumUnique, List.Count - NumUnique);
}

如果需要比较复杂的对象，则需要在Distinct()方法中传递一个compararer对象。

private void GetDistinctItemList(List<MyListItem> _listWithDuplicates)
{
    //It might be a good idea to create MyListItemComparer 
    //elsewhere and cache it for performance.
    List<MyListItem> _listWithoutDuplicates = _listWithDuplicates.Distinct(new MyListItemComparer()).ToList();
        
    //Choose the line below instead, if you have a situation where there is a chance to change the list while Distinct() is running.
    //ToArray() is used to solve "Collection was modified; enumeration operation may not execute" error.
    //List<MyListItem> _listWithoutDuplicates = _listWithDuplicates.ToArray().Distinct(new MyListItemComparer()).ToList();

    return _listWithoutDuplicates;
}

假设你有另外两个类，比如:

public class MyListItemComparer : IEqualityComparer<MyListItem>
{
    public bool Equals(MyListItem x, MyListItem y)
    {
        return x != null 
               && y != null 
               && x.A == y.A 
               && x.B.Equals(y.B); 
               && x.C.ToString().Equals(y.C.ToString());
    }

    public int GetHashCode(MyListItem codeh)
    {
        return codeh.GetHashCode();
    }
}

And:

public class MyListItem
{
    public int A { get; }
    public string B { get; }
    public MyEnum C { get; }

    public MyListItem(int a, string b, MyEnum c)
    {
        A = a;
        B = b;
        C = c;
    }
}

  public static void RemoveDuplicates<T>(IList<T> list )
  {
     if (list == null)
     {
        return;
     }
     int i = 1;
     while(i<list.Count)
     {
        int j = 0;
        bool remove = false;
        while (j < i && !remove)
        {
           if (list[i].Equals(list[j]))
           {
              remove = true;
           }
           j++;
        }
        if (remove)
        {
           list.RemoveAt(i);
        }
        else
        {
           i++;
        }
     }  
  }

这里有一个扩展的方法来删除相邻的副本原位。首先调用Sort()并传入相同的ic比较器。这应该比Lasse V. Karlsen的版本更有效，后者重复调用RemoveAt(导致多次块内存移动)。

public static void RemoveAdjacentDuplicates<T>(this List<T> List, IComparer<T> Comparer)
{
    int NumUnique = 0;
    for (int i = 0; i < List.Count; i++)
        if ((i == 0) || (Comparer.Compare(List[NumUnique - 1], List[i]) != 0))
            List[NumUnique++] = List[i];
    List.RemoveRange(NumUnique, List.Count - NumUnique);
}

作为一个辅助方法(没有Linq):

public static List<T> Distinct<T>(this List<T> list)
{
    return (new HashSet<T>(list)).ToList();
}

使用HashSet: list = new HashSet<T>(list).ToList();