C++

23.5    Template Classes

The template technique, as you have just learned with function templates, is not limited to functions but can also be used with classes. To be precise, C++ would not be as popular and beloved as it is today without class templates. The standard library defines many class templates, of which you have already used std::vector or std::string. With std::vector, you specified the type in the angle brackets. std::string, on the other hand, is an instantiation of the char type and is internally defined as follows:

using string = basic_string<char>;  

In addition to the standard container classes like std::vector, std::list, and so on, the stream classes for input/output (see Chapter 26) are also mostly implemented as instantiations ...