IList.Add Method
.NET Framework 4
Adds an item to the IList.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
- Type: System.Object
The object to add to the IList.
Return Value
Type: System.Int32The position into which the new element was inserted, or -1 to indicate that the item was not inserted into the collection.
| Exception | Condition |
|---|---|
| NotSupportedException | The IList is read-only. -or- The IList has a fixed size. |
The following example demonstrates the implementation of the IList interface to create a simple, fixed-size list. This code is part of a larger example 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 SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.