Beginning Programming All-in-One For Dummies, 2nd Edition

Chapter 3

Collections and Dictionaries

IN THIS CHAPTER

Storing data in a collection

Organizing data in a dictionary

Understanding hash tables and collisions

An array can be handy when you need to store the same type of information, such as a group of integers. However, if you need to store different information, such as both integers and strings, and you aren’t sure how many items you need to store, you probably can’t use an array. Instead, you can use a collection or a dictionary.

A collection (also called a list in some languages) acts like a resizable array that can hold different data types at the same time while identifying each chunk of data with a number. A dictionary acts like a collection that identifies each chunk of data with a unique key.

The purpose of both collections and dictionaries is to make it easier to store different types of data and retrieve them again with the size and single data type restrictions of an array.

Using a Collection

A collection acts like a super array that can grow and expand without requiring any special commands. In addition, a collection can store different data types (such as integers or strings) or even other data structures, such as ...