Sometimes a data type is best represented as a collection of one or more data types.
Imagine you're writing a program to model a train.
One way you would represent a train as a data type would be a collection of train car types.
Each train car type can further be a collection of passenger and luggage data types and so on.
Collections don't have to hold the same type.
Think about modeling a shopping bag. It can hold toys, groceries, and clothing for example.
Lists
A List is a data type that represents a sequential collection.
Usually, you can mix elements with different data types in a list, but some languages only let you use one data type in a list.
Lists items commonly have a direction:
Which can also point both ways if needed:
Sometimes we can see lists written using square brackets [ ], with the values separated by commas inside.
The above is a special kind of list called an array.
An array is a list where each item can be accessed based on its position.
Dictionaries
Dictionaries are associative collections that represent key/value pairs.
The name is inspired by our everyday language dictionaries, which are collections of word/definition pairs.
One way to write a dictionary is using curly braces ({ }):
💡 You can leave comments in your code. Usually, single-line comments are marked using //, but some programming languages might use a different way.
In this example, name is the key, and "Artemis" is the value.
