System.Collections.Hashtable.ContainsKey Method

Determines whether the Hashtable contains a specific key.

Syntax

public virtual bool ContainsKey (object key)

Parameters

key
The key to locate in the Hashtable.

Returns

true if the Hashtable contains an element with the specified key; otherwise, false.

Exceptions

TypeReason
ArgumentNullException key is null.

Remarks

This method behaves exactly as Hashtable.Contains(object).

This method is an O(1) operation.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ object.Equals(object) and IComparable.CompareTo(object) methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the object.Equals(object) and IComparable.CompareTo(object) methods of the item parameter on the objects in the collection.

Requirements

Namespace: System.Collections
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0