Introducing C++

Chapter 10. Classes: Member Variables and Member Functions

You now know about various fundamental types in C++, including numerical types, characters, and strings. You have used classes from the standard library a few times, including class templates like std::vector. This chapter will show you how to write your own classes.

Classes allow you to bundle together related elements. For example, you could bundle a stock name together with a starting price and a way to generate or input price updates. Namespaces also group related functions and types, but classes give you more options. Bundling elements into a class gives you a new type, which allows you to add new stock types to your trading game easily. You also give classes names, conveying meaning, which can make your code easier to read.

Around 1979, C++ started as “C with classes,” designed by Bjarne Stroustrup. He found classes useful for working on larger codebases because they provide a way to think at a higher level. You can think about a stock, rather than a name, a price, and a way to get a new price. Furthermore, the name is a std::string class, which is a higher-level concept than a C-style char pointer. As you have seen, there is much more to C++ than classes, but they are a fundamental part of many C++ codebases.

Let’s create a class first, starting with some data and then adding behavior. By the end of this chapter, you will be able to create a std::vector of various stocks. You will then be a step closer to a bigger ...