Understanding template parameters
So far in the book, we have seen multiple examples of templates with one or more parameters. In all these examples, the parameters represented types supplied at instantiation, either explicitly by the user, or implicitly by the compiler when it could deduce them. These kinds of parameters are called type template parameters. However, templates can also have non-type template parameters and template template parameters. In the following sections, we'll explore all of them.
Type template parameters
As already mentioned, these are parameters representing types supplied as arguments during the template instantiation. They are introduced either with the
typename or the
class keyword. There is no difference between using these two keywords. A type template parameter can have a default value, which is a type. This is specified the same way you would specify a default value for a function parameter. Examples for these are shown in the following...