Gets or sets the value associated with the specified key.
Assembly: System (in System.dll)
abstract Item : key:string -> string with get, set override Item : key:string -> string with get, set
- Type: System.String
The key whose value to get or set.
Property ValueType: System.String
The value associated with the specified key. If the specified key is not found, Get returns a null reference (Nothing in Visual Basic), and Set creates a new entry with the specified key.
The key is handled in a case-insensitive manner; it is translated to lowercase before it is used.
A key cannot be a null reference (Nothing in Visual Basic), but a value can. To distinguish between a null reference (Nothing in Visual Basic) that is returned because the specified key is not found and a null reference (Nothing in Visual Basic) that is returned because the value of the specified key is a null reference (Nothing in Visual Basic), use the ContainsKey method to determine if the key exists in the list.
The C# language uses the this keyword to define the indexers instead of implementing the property. Visual Basic implements as a default property, which provides the same indexing functionality.
Retrieving the value of this property is an O(1) operation; setting the property is also an O(1) operation.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.