Determines if the StringDictionary contains a specific key.
Assembly: System (in System.dll)
abstract ContainsKey : key:string -> bool override ContainsKey : key:string -> bool
The key is a null reference (Nothing in Visual Basic).
The key is handled in a case-insensitive manner; it is translated to lowercase before it is used.
This method is an O(1) operation.
Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.