IList Interface
Assembly: mscorlib (in mscorlib.dll)
IList is a descendant of the ICollection interface and is the base interface of all non-generic lists. IList implementations fall into three categories: read-only, fixed-size, and variable-size. A read-only IList cannot be modified. A fixed-size IList does not allow the addition or removal of elements, but it allows the modification of existing elements. A variable-size IList allows the addition, removal, and modification of elements.
For the generic version of this interface, see System.Collections.Generic.IList.
The following example demonstrates the implementation of the IList interface to create a simple list, fixed-size list.
using System; using System.Collections; class Program { static void Main() { SimpleList test = new SimpleList(); // Populate the List Console.WriteLine("Populate the List"); test.Add("one"); test.Add("two"); test.Add("three"); test.Add("four"); test.Add("five"); test.Add("six"); test.Add("seven"); test.Add("eight"); test.PrintContents(); Console.WriteLine(); // Remove elements from the list Console.WriteLine("Remove elements from the list"); test.Remove("six"); test.Remove("eight"); test.PrintContents(); Console.WriteLine(); // Add an element to the end of the list Console.WriteLine("Add an element to the end of the list"); test.Add("nine"); test.PrintContents(); Console.WriteLine(); // Insert an element into the middle of the list Console.WriteLine("Insert an element into the middle of the list"); test.Insert(4, "number"); test.PrintContents(); Console.WriteLine(); // Check for specific elements in the list Console.WriteLine("Check for specific elements in the list"); Console.WriteLine("List contains \"three\": {0}", test.Contains("three")); Console.WriteLine("List contains \"ten\": {0}", test.Contains("ten")); } } // class Program 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(); } } // This code produces output similar to the following: // Populate the List: // List has a capacity of 8 and currently has 8 elements. // List contents: one two three four five six seven eight // // Remove elements from the list: // List has a capacity of 8 and currently has 6 elements. // List contents: one two three four five seven // // Add an element to the end of the list: // List has a capacity of 8 and currently has 7 elements. // List contents: one two three four five seven nine // // Insert an element into the middle of the list: // List has a capacity of 8 and currently has 8 elements. // List contents: one two three four number five seven nine // // Check for specific elements in the list: // List contains "three": True // List contains "ten": False
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.