Array slices in C#

Asked 2009-01-02T10:49:05.353

316

How do you do it? Given a byte array:

byte[] foo = new byte[4096];

How would I get the first x bytes of the array as a separate array? (Specifically, I need it as an IEnumerable<byte>)

This is for working with Sockets. I figure the easiest way would be array slicing, similar to Perls syntax:

@bar = @foo[0..40];

Which would return the first 41 elements into the @bar array. Is there something in C# that I'm just missing, or is there some other thing I should be doing?

LINQ is an option for me (.NET 3.5), if that helps any.

c# arrays

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2 Answers

You could use a wrapper around the original array (which is IList), like in this (untested) piece of code.

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 NotSuppo


                        
                        
                            answered 2009-01-02T11:42:10.243


            
            
                
                    
                        
                            
                            
                        
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                        I do not think C# supports the Range semantics. You could write an extension method though, like:

public static IEnumerator<Byte> Range(this byte[] array, int start, int end);


But like others have said if you do not need to set a start index then Take is all you need.

                        
                        
                            answered 2009-01-02T10:53:27.717



        
        
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