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
)

Parameters

key
Type: System.Object

The key to locate in the OrderedDictionary collection.

Return Value

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

Implements

IDictionary.Contains(Object)

Using the Item property can return a null value if the key does not exist or if the key is null. 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"))
    {
        myOrderedDictionary.Remove("keyToDelete");
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0
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