OrderedDictionary.Contains(Object) Method
Definition
Important
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Determines whether the OrderedDictionary collection contains a specific key.
public:
virtual bool Contains(System::Object ^ key);
public bool Contains (object key);
abstract member Contains : obj -> bool
override this.Contains : obj -> bool
Public Function Contains (key As Object) As Boolean
Parameters
- key
- Object
The key to locate in the OrderedDictionary collection.
Returns
true
if the OrderedDictionary collection contains an element with the specified key; otherwise, false
.
Implements
Examples
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");
}
}
// 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");
}
}
' Modifying the OrderedDictionary
If Not myOrderedDictionary.IsReadOnly Then
' 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")) Then
myOrderedDictionary.Remove("keyToDelete")
End If
End If
Remarks
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.
Applies to
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