System.Collections.Hashtable.ContainsKey Method

Determines whether the current instance contains an entry with the specified key.

Syntax

public virtual bool ContainsKey (object key)

Parameters

key
The key of the entry to locate in the current instance.

Returns

true if the current instance contains an entry with key; otherwise, false.

Exceptions

TypeReason
ArgumentNullException key is null.

Remarks

Operation
As described above.

This method uses Hashtable.KeyEquals(object, object) to compare key to the keys in the current instance.

Note: For the default implementation, this method has a constant (O(1)) lookup time.

Requirements

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