IList.Remove Method

Removes the first occurrence of a specific object from the IList.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)

void Remove(
	Object value
)

Parameters

value
Type: System.Object

The Object to remove from the IList.

ExceptionCondition
NotSupportedException

The IList is read-only.

-or-

The IList has a fixed size.

In collections of contiguous elements, such as lists, the elements that follow the removed element move up to occupy the vacated spot. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hash table. If value is not found in the IList, the IList remains unchanged and no exception is thrown.

Notes to Implementers:

If value is not in the list, the Remove method should do nothing. In particular, it should not throw an exception.

The following example demonstrates the implementation of the IList interface to create a simple, fixed-size list. This code example is part of a larger example provided for the IList interface.

class SimpleList : IList
{
    private object[] _contents = new object[8];
    private int _count;

    public SimpleList()
    {
        _count = 0;
    }

    // IList Members 
    public int Add(object value)
    {
        if (_count < _contents.Length)
        {
            _contents[_count] = value;
            _count++;

            return (_count - 1);
        }
        else
        {
            return -1;
        }
    }

    public void Clear()
    {
        _count = 0;
    }

    public bool Contains(object value)
    {
        bool inList = false;
        for (int i = 0; i < Count; i++)
        {
            if (_contents[i] == value)
            {
                inList = true;
                break;
            }
        }
        return inList;
    }

    public int IndexOf(object value)
    {
        int itemIndex = -1;
        for (int i = 0; i < Count; i++)
        {
            if (_contents[i] == value)
            {
                itemIndex = i;
                break;
            }
        }
        return itemIndex;
    }

    public void Insert(int index, object value)
    {
        if ((_count + 1 <= _contents.Length) && (index < Count) && (index >= 0))
        {
            _count++;

            for (int i = Count - 1; i > index; i--)
            {
                _contents[i] = _contents[i - 1];
            }
            _contents[index] = value;
        }
    }

    public bool IsFixedSize
    {
        get
        {
            return true;
        }
    }

    public bool IsReadOnly
    {
        get
        {
            return false;
        }
    }

    public void Remove(object value)
    {
        RemoveAt(IndexOf(value));
    }

    public void RemoveAt(int index)
    {
        if ((index >= 0) && (index < Count))
        {
            for (int i = index; i < Count - 1; i++)
            {
                _contents[i] = _contents[i + 1];
            }
            _count--;
        }
    }

    public object this[int index]
    {
        get
        {
            return _contents[index];
        }
        set
        {
            _contents[index] = value;
        }
    }

    // ICollection Members 

    public void CopyTo(Array array, int index)
    {
        int j = index;
        for (int i = 0; i < Count; i++)
        {
            array.SetValue(_contents[i], j);
            j++;
        }
    }

    public int Count
    {
        get
        {
            return _count;
        }
    }

    public bool IsSynchronized
    {
        get
        {
            return false;
        }
    }

    // Return the current instance since the underlying store is not 
    // publicly available. 
    public object SyncRoot
    {
        get
        {
            return this;
        }
    }

    // IEnumerable Members 

    public IEnumerator GetEnumerator()
    {
        // Refer to the IEnumerator documentation for an example of 
        // implementing an enumerator. 
        throw new Exception("The method or operation is not implemented.");
    }

    public void PrintContents()
    {
        Console.WriteLine("List has a capacity of {0} and currently has {1} elements.", _contents.Length, _count);
        Console.Write("List contents:");
        for (int i = 0; i < Count; i++)
        {
            Console.Write(" {0}", _contents[i]);
        }
        Console.WriteLine();
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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