4.1. Introduction to Containers

4.1. Introduction to Containers
	Chapter 4. Lists

[ fromfile: lists.xml id: introcontainers ]

Following are a few good reasons to avoid using arrays in C++:
- Neither the compiler nor the runtime system checks array subscripts to make sure that they are within the correct range.
- A programmer using an array has the responsibility to write extra code to do the range checking.
- Writing a safe wrapper for a variable-sized heap array requires deep knowledge of both C and C++.
- Inserting, prepending, or appending elements to an array can be expensive operations (in terms of both runtime and developer time).

std::list and QList are the most basic generic containers in their respective libraries.
They are similar to each other in interface (the way they are used from client code).
They differ in implementation (the way they behave at runtime).
Both libraries also provide several other generic containers that are optimized for particular types of application.

We used the term generic containers because

Generics are classes or functions that accept template (Section 11.1) parameters so that they can be used with different types of data.
Containers (Section 6.7) are objects that can contain other objects.

To use a generic container, client code must contain a declaration that answers the question: "Container of what?"

For example:

  QList<double>  doubleList;
  QList<Thing>  thingList;

With a single function call, items can be added, removed, swapped, queried, cleared, moved, located, and counted in a variety of ways.


Chapter 4. Lists		4.2. Iterators