Operations on Dictionaries

Operations

You can perform the following operations on dictionaries:

• Create – Create a new empty dictionary.

  Syntax: new dictionary(type, type)

  Type: A vector of the declared type is returned.

  Example: d := new dictionary(integer, string);

• Get value by key – Get a value from the dictionary by key. If there is no such key in the dictionary, return null.

  Syntax: dictionary[key]

  Type: The key must have the type of the keys of the dictionary. The function returns a value of the type of the values held in the dictionary.

  Example: counter[input]

• Assign a value by key – Associate a value with a key in the dictionary.

  Syntax: dictionary[key] := value

  Type: The key and value must match the key type and value type of the dictionary. The function returns the updated dictionary.

  Example: counter[input] := 3

• Remove a key/value pair – Remove a key, and its associated value, from the dictionary.

  Syntax: remove(dictionary, key)

  Type: The key must match the key type of the dictionary. The function returns an integer: 0 if the key was not present, and 1 otherwise.

  Example: remove(counter, input)

• Clear a dictionary – Remove all key/value pairs from the dictionary.

  Syntax: clear(dictionary)

  The function returns the cleared dictionary.

  Example: clear(counter)

• Test for emptiness – Test a dictionary for emptiness.

  Syntax: empty(dictionary)

  The function returns an integer: 1 if the dictionary is empty, 0 if not empty.

  Example: empty(counter)

You can also iterate through all the key/value pairs in the dictionary using a "for" loop.