Which method checks if an item with a given key exists in a dictionary and returns a Boolean result?

Which method checks if an item with a given key exists in a dictionary and returns a Boolean result?

• A. VarName.ContainsKey(Key)
• B. VarName.TryGetValue(Key, Value)
• C. VarName.Item(Key)
• D. VarName.Count

Answer: (B)

The method that checks if an item with a given key exists in a dictionary and returns a Boolean result is indeed the one that uses the ContainsKey function. This method directly evaluates whether the specified key is present in the dictionary and returns true if it is found and false otherwise. The chosen option effectively provides a straightforward way to confirm the existence of a key without modifying the dictionary or retrieving the associated value. It is efficient and directly addresses the task of key existence checks. In contrast, other options might not serve this purpose. For example, TryGetValue is designed to attempt to retrieve the value associated with the specified key and returns a Boolean indicating if the operation succeeded, but it does not explicitly focus only on checking for the key's existence. The Item method, or indexer, is primarily used to access values by key and will throw an exception if the key is not found, which does not align with a simple existence check. Lastly, the Count method simply returns the number of key-value pairs present in the dictionary and does not pertain to checking for a specific key's existence.

The method that checks if an item with a given key exists in a dictionary and returns a Boolean result is indeed the one that uses the ContainsKey function. This method directly evaluates whether the specified key is present in the dictionary and returns true if it is found and false otherwise.

The chosen option effectively provides a straightforward way to confirm the existence of a key without modifying the dictionary or retrieving the associated value. It is efficient and directly addresses the task of key existence checks.

In contrast, other options might not serve this purpose. For example, TryGetValue is designed to attempt to retrieve the value associated with the specified key and returns a Boolean indicating if the operation succeeded, but it does not explicitly focus only on checking for the key's existence. The Item method, or indexer, is primarily used to access values by key and will throw an exception if the key is not found, which does not align with a simple existence check. Lastly, the Count method simply returns the number of key-value pairs present in the dictionary and does not pertain to checking for a specific key's existence.