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OrderedDictionary.Contains Method

Determines whether the OrderedDictionary collection contains a specific key.

Namespace: System.Collections.Specialized
Assembly: System (in system.dll)

public bool Contains (
	Object key
public final boolean Contains (
	Object key
public final function Contains (
	key : Object
) : boolean
Not applicable.



The key to locate in the OrderedDictionary collection.

Return Value

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

Using the Item property can return a null value if the key does not exist or if the key is a null reference (Nothing in Visual Basic). Use the Contains method to determine if a specific key exists in the OrderedDictionary collection.

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.

The following code example demonstrates the modification of an OrderedDictionary collection. In this example, the Contains method is used to determine if an entry exists before attempting to remove it. This code is part of a larger code example that can be viewed at OrderedDictionary.

// Modifying the OrderedDictionary
if (!myOrderedDictionary.IsReadOnly)
    // Insert a new key to the beginning of the OrderedDictionary
    myOrderedDictionary.Insert(0, "insertedKey1", "insertedValue1");

    // Modify the value of the entry with the key "testKey2"
    myOrderedDictionary["testKey2"] = "modifiedValue";

    // Remove the last entry from the OrderedDictionary: "testKey3"
    myOrderedDictionary.RemoveAt(myOrderedDictionary.Count - 1);

    // Remove the "keyToDelete" entry, if it exists
    if (myOrderedDictionary.Contains("keyToDelete"))

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0