你可以参加微软的课程:

internal class Set<TElement>
{
    private int[] _buckets;
    private Slot[] _slots;
    private int _count;
    private int _freeList;
    private readonly IEqualityComparer<TElement> _comparer;

    public Set()
        : this(null)
    {
    }

    public Set(IEqualityComparer<TElement> comparer)
    {
        if (comparer == null)
            comparer = EqualityComparer<TElement>.Default;
        _comparer = comparer;
        _buckets = new int[7];
        _slots = new Slot[7];
        _freeList = -1;
    }

    public bool Add(TElement value)
    {
        return !Find(value, true);
    }

    public bool Contains(TElement value)
    {
        return Find(value, false);
    }

    public bool Remove(TElement value)
    {
        var hashCode = InternalGetHashCode(value);
        var index1 = hashCode % _buckets.Length;
        var index2 = -1;
        for (var index3 = _buckets[index1] - 1; index3 >= 0; index3 = _slots[index3].Next)
        {
            if (_slots[index3].HashCode == hashCode && _comparer.Equals(_slots[index3].Value, value))
            {
                if (index2 < 0)
                    _buckets[index1] = _slots[index3].Next + 1;
                else
                    _slots[index2].Next = _slots[index3].Next;
                _slots[index3].HashCode = -1;
                _slots[index3].Value = default(TElement);
                _slots[index3].Next = _freeList;
                _freeList = index3;
                return true;
            }
            index2 = index3;
        }
        return false;
    }

    private bool Find(TElement value, bool add)
    {
        var hashCode = InternalGetHashCode(value);
        for (var index = _buckets[hashCode % _buckets.Length] - 1; index >= 0; index = _slots[index].Next)
        {
            if (_slots[index].HashCode == hashCode && _comparer.Equals(_slots[index].Value, value))
                return true;
        }
        if (add)
        {
            int index1;
            if (_freeList >= 0)
            {
                index1 = _freeList;
                _freeList = _slots[index1].Next;
            }
            else
            {
                if (_count == _slots.Length)
                    Resize();
                index1 = _count;
                ++_count;
            }
            int index2 = hashCode % _buckets.Length;
            _slots[index1].HashCode = hashCode;
            _slots[index1].Value = value;
            _slots[index1].Next = _buckets[index2] - 1;
            _buckets[index2] = index1 + 1;
        }
        return false;
    }

    private void Resize()
    {
        var length = checked(_count * 2 + 1);
        var numArray = new int[length];
        var slotArray = new Slot[length];
        Array.Copy(_slots, 0, slotArray, 0, _count);
        for (var index1 = 0; index1 < _count; ++index1)
        {
            int index2 = slotArray[index1].HashCode % length;
            slotArray[index1].Next = numArray[index2] - 1;
            numArray[index2] = index1 + 1;
        }
        _buckets = numArray;
        _slots = slotArray;
    }

    internal int InternalGetHashCode(TElement value)
    {
        if (value != null)
            return _comparer.GetHashCode(value) & int.MaxValue;
        return 0;
    }

    internal struct Slot
    {
        internal int HashCode;
        internal TElement Value;
        internal int Next;
    }
}

然后

public static T[] GetSub<T>(this T[] first, T[] second)
    {
        var items = IntersectIteratorWithIndex(first, second);
        if (!items.Any()) return new T[] { };


        var index = items.First().Item2;
        var length = first.Count() - index;
        var subArray = new T[length];
        Array.Copy(first, index, subArray, 0, length);
        return subArray;
    }

    private static IEnumerable<Tuple<T, Int32>> IntersectIteratorWithIndex<T>(IEnumerable<T> first, IEnumerable<T> second)
    {
        var firstList = first.ToList();
        var set = new Set<T>();
        foreach (var i in second)
            set.Add(i);
        foreach (var i in firstList)
        {
            if (set.Remove(i))
                yield return new Tuple<T, Int32>(i, firstList.IndexOf(i));
        }
    }

在c# 8.0中，你现在可以像Python一样做许多更漂亮的工作，包括反向索引和范围，例如:

int[] list = {1, 2, 3, 4, 5, 6};
var list2 = list[2..5].Clone() as int[]; // 3, 4, 5
var list3 = list[..5].Clone() as int[];  // 1, 2, 3, 4, 5
var list4 = list[^4..^0].Clone() as int[];  // reverse index

在c# 8中，他们引入了一个新的范围和索引类型，可以这样使用:

int[] a = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
Index i1 = 3;  // number 3 from beginning
Index i2 = ^4; // number 4 from end
var slice = a[i1..i2]; // { 3, 4, 5 }

引用:

https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-core-3-0#ranges-and-indices https://devblogs.microsoft.com/dotnet/building-c-8-0/

public   static   T[]   SubArray<T>(T[] data, int index, int length)
        {
            List<T> retVal = new List<T>();
            if (data == null || data.Length == 0)
                return retVal.ToArray();
            bool startRead = false;
            int count = 0;
            for (int i = 0; i < data.Length; i++)
            {
                if (i == index && !startRead)
                    startRead = true;
                if (startRead)
                {

                    retVal.Add(data[i]);
                    count++;

                    if (count == length)
                        break;
                }
            }
            return retVal.ToArray();
        }

数组中。ConstrainedCopy将工作。

public static void ConstrainedCopy (
    Array sourceArray,
    int sourceIndex,
    Array destinationArray,
    int destinationIndex,
    int length
)

这个怎么样:

public T[] CloneCopy(T[] array, int startIndex, int endIndex) where T : ICloneable
{
    T[] retArray = new T[endIndex - startIndex];
    for (int i = startIndex; i < endIndex; i++)
    {
        array[i - startIndex] = array[i].Clone();
    }
    return retArray;

}

然后，您需要在所有需要使用ICloneable的类上实现ICloneable接口，但这样就可以了。