Assembly: mscorlib (in mscorlib.dll)
The object to locate in the List. The value can be a null reference (Nothing in Visual Basic) for reference types.
Return ValueThe zero-based index of the first occurrence of item within the entire Collection, if found; otherwise, -1.
The Collection is searched forward starting at the first element and ending at the last element.
This method determines equality using the default equality comparer EqualityComparer.Default for T, the type of values in the list.
This method performs a linear search; therefore, the average execution time is proportional to Count. That is, this method is an O(n) operation, where n is Count.
The following code example demonstrates many of the properties and methods of Collection. The code example creates a collection of strings, uses the Add method to add several strings, displays the Count, and lists the strings. The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. The example inserts a string using the Insert method and retrieves and sets strings using the default Item property (the indexer in C#). The example removes strings by string identity using the Remove method and by index using the RemoveAt method. Finally, the Clear method is used to clear all strings from the collection.
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 EditionThe Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.