这可能是一个解决方案:

var result = foo.Slice(40, int.MaxValue);

然后结果是一个IEnumerable< IEnumerable<字节>>，其中第一个IEnumerable<字节>包含foo的前40个字节，第二个IEnumerable<字节>包含其余的字节。

我写了一个包装类，整个迭代是懒惰的，希望对大家有所帮助:

public static class CollectionSlicer
{
    public static IEnumerable<IEnumerable<T>> Slice<T>(this IEnumerable<T> source, params int[] steps)
    {
        if (!steps.Any(step => step != 0))
        {
            throw new InvalidOperationException("Can't slice a collection with step length 0.");
        }
        return new Slicer<T>(source.GetEnumerator(), steps).Slice();
    }
}

public sealed class Slicer<T>
{
    public Slicer(IEnumerator<T> iterator, int[] steps)
    {
        _iterator = iterator;
        _steps = steps;
        _index = 0;
        _currentStep = 0;
        _isHasNext = true;
    }

    public int Index
    {
        get { return _index; }
    }

    public IEnumerable<IEnumerable<T>> Slice()
    {
        var length = _steps.Length;
        var index = 1;
        var step = 0;

        for (var i = 0; _isHasNext; ++i)
        {
            if (i < length)
            {
                step = _steps[i];
                _currentStep = step - 1;
            }

            while (_index < index && _isHasNext)
            {
                _isHasNext = MoveNext();
            }

            if (_isHasNext)
            {
                yield return SliceInternal();
                index += step;
            }
        }
    }

    private IEnumerable<T> SliceInternal()
    {
        if (_currentStep == -1) yield break;
        yield return _iterator.Current;

        for (var count = 0; count < _currentStep && _isHasNext; ++count)
        {
            _isHasNext = MoveNext();

            if (_isHasNext)
            {
                yield return _iterator.Current;
            }
        }
    }

    private bool MoveNext()
    {
        ++_index;
        return _iterator.MoveNext();
    }

    private readonly IEnumerator<T> _iterator;
    private readonly int[] _steps;
    private volatile bool _isHasNext;
    private volatile int _currentStep;
    private volatile int _index;
}

对于字节数组，System.Buffer.BlockCopy会给你最好的性能。

下面是一个使用泛型的扩展函数，其行为类似于PHP函数array_slice。允许负偏移量和负长度。

public static class Extensions
{
    public static T[] Slice<T>(this T[] arr, int offset, int length)
    {
        int start, end;

        // Determine start index, handling negative offset.
        if (offset < 0)
            start = arr.Length + offset;
        else
            start = offset;

        // Clamp start index to the bounds of the input array.
        if (start < 0)
            start = 0;
        else if (start > arr.Length)
            start = arr.Length;

        // Determine end index, handling negative length.
        if (length < 0)
            end = arr.Length + length;
        else
            end = start + length;

        // Clamp end index to the bounds of the input array.
        if (end < 0)
            end = 0;
        if (end > arr.Length)
            end = arr.Length;

        // Get the array slice.
        int len = end - start;
        T[] result = new T[len];
        for (int i = 0; i < len; i++)
        {
            result[i] = arr[start + i];
        }
        return result;
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace data_seniens
{
    class Program
    {
        static void Main(string[] args)
        {
            //new list
            float [] x=new float[]{11.25f,18.0f,20.0f,10.75f,9.50f, 11.25f, 18.0f, 20.0f, 10.75f, 9.50f };

            //variable
            float eat_sleep_area=x[1]+x[3];
            //print
            foreach (var VARIABLE in x)
            {
                if (VARIABLE < x[7])
                {
                    Console.WriteLine(VARIABLE);
                }
            }



            //keep app run
        Console.ReadLine();
        }
    }
}

您可以对原始数组(即IList)使用包装器，就像下面(未经测试的)代码一样。

public class SubList<T> : IList<T>
{
    #region Fields

    private readonly int startIndex;
    private readonly int endIndex;
    private readonly int count;
    private readonly IList<T> source;

    #endregion

    public SubList(IList<T> source, int startIndex, int count)
    {
        this.source = source;
        this.startIndex = startIndex;
        this.count = count;
        this.endIndex = this.startIndex + this.count - 1;
    }

    #region IList<T> Members

    public int IndexOf(T item)
    {
        if (item != null)
        {
            for (int i = this.startIndex; i <= this.endIndex; i++)
            {
                if (item.Equals(this.source[i]))
                    return i;
            }
        }
        else
        {
            for (int i = this.startIndex; i <= this.endIndex; i++)
            {
                if (this.source[i] == null)
                    return i;
            }
        }
        return -1;
    }

    public void Insert(int index, T item)
    {
        throw new NotSupportedException();
    }

    public void RemoveAt(int index)
    {
        throw new NotSupportedException();
    }

    public T this[int index]
    {
        get
        {
            if (index >= 0 && index < this.count)
                return this.source[index + this.startIndex];
            else
                throw new IndexOutOfRangeException("index");
        }
        set
        {
            if (index >= 0 && index < this.count)
                this.source[index + this.startIndex] = value;
            else
                throw new IndexOutOfRangeException("index");
        }
    }

    #endregion

    #region ICollection<T> Members

    public void Add(T item)
    {
        throw new NotSupportedException();
    }

    public void Clear()
    {
        throw new NotSupportedException();
    }

    public bool Contains(T item)
    {
        return this.IndexOf(item) >= 0;
    }

    public void CopyTo(T[] array, int arrayIndex)
    {
        for (int i=0; i<this.count; i++)
        {
            array[arrayIndex + i] = this.source[i + this.startIndex];
        }
    }

    public int Count
    {
        get { return this.count; }
    }

    public bool IsReadOnly
    {
        get { return true; }
    }

    public bool Remove(T item)
    {
        throw new NotSupportedException();
    }

    #endregion

    #region IEnumerable<T> Members

    public IEnumerator<T> GetEnumerator()
    {
        for (int i = this.startIndex; i < this.endIndex; i++)
        {
            yield return this.source[i];
        }
    }

    #endregion

    #region IEnumerable Members

    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }

    #endregion
}

您可以使用Take扩展方法

var array = new byte[] {1, 2, 3, 4};
var firstTwoItems = array.Take(2);