ListDictionary::Contains Method (Object^)
.NET Framework (current version)
Determines whether the ListDictionary contains a specific key.
Assembly: System (in System.dll)
Parameters
- key
-
Type:
System::Object^
The key to locate in the ListDictionary.
Return Value
Type: System::Booleantrue if the ListDictionary contains an entry with the specified key; otherwise, false.
Implements
IDictionary::Contains(Object^)| Exception | Condition |
|---|---|
| ArgumentNullException | key is null. |
This method is an O(n) operation, where n is Count.
Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on key 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 searches for an element in a ListDictionary.
#using <System.dll> using namespace System; using namespace System::Collections; using namespace System::Collections::Specialized; void PrintKeysAndValues( IDictionary^ myCol ) { Console::WriteLine( " KEY VALUE" ); IEnumerator^ myEnum = myCol->GetEnumerator(); while ( myEnum->MoveNext() ) { DictionaryEntry de = safe_cast<DictionaryEntry>(myEnum->Current); Console::WriteLine( " {0,-25} {1}", de.Key, de.Value ); } Console::WriteLine(); } int main() { // Creates and initializes a new ListDictionary. ListDictionary^ myCol = gcnew ListDictionary; myCol->Add( "Braeburn Apples", "1.49" ); myCol->Add( "Fuji Apples", "1.29" ); myCol->Add( "Gala Apples", "1.49" ); myCol->Add( "Golden Delicious Apples", "1.29" ); myCol->Add( "Granny Smith Apples", "0.89" ); myCol->Add( "Red Delicious Apples", "0.99" ); // Displays the values in the ListDictionary in three different ways. Console::WriteLine( "Initial contents of the ListDictionary:" ); PrintKeysAndValues( myCol ); // Searches for a key. if ( myCol->Contains( "Kiwis" ) ) Console::WriteLine( "The collection contains the key \"Kiwis\"." ); else Console::WriteLine( "The collection does not contain the key \"Kiwis\"." ); Console::WriteLine(); } /* This code produces the following output. Initial contents of the ListDictionary: KEY VALUE Braeburn Apples 1.49 Fuji Apples 1.29 Gala Apples 1.49 Golden Delicious Apples 1.29 Granny Smith Apples 0.89 Red Delicious Apples 0.99 The collection does not contain the key "Kiwis". */
Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Available since 10
.NET Framework
Available since 1.1
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