Goodness and evil never share the same road, just as ice and charcoal never share the same container.
As people began to develop code, they noticed that they were coding the same things over and over again. For example, in every large C program, you'll probably find an implementation of a linked list. Since it's better to reuse than to rewrite, the designers of C++ have added a library of common containers (lists, arrays, and others) to the language. This library is known as the Standard Template Library or STL.
These containers are designed as templates so that they can hold almost anything. The library provides not only the containers but also iterators that make access to the contents of a container easier.
Finally, there are the algorithms that perform common functions on a container, such as sorting, merging two containers, locating elements, and other such functions.
In this section we take a look at the basic concepts that went into the design of the STL and how all these design elements come together to provide a very robust and flexible way of handling items.
The core of the STL is the container. We're already familiar with a couple of STL container types, the vector (a single-dimension array) and the stack.
The STL divides containers into sequences, which store their elements in order, and associative containers, in which elements are accessed using a key value.
The basic STL containers are: