Question

In the Bjarne Stroustrup C++ Book (chapter 13, page 331), it said that “a template parameter can be used in the definition of subsequent template parameter”. And it gives the following code:

template<class T, T def_val> class Cont{ /* ... */ }

Can anyone provide an example of how to use this template. For example, how to initialize an object of Cont? It look to me that “def_val” is not a type argument, and should not be placed in <>. Am I wrong?

Thanks a lot

Answer 1

You can do something like this:

Cont<int, 6> cnt;
//        ^ as long as this is of type T (in this case int)
// def_val will be of type int and have a value of 6

Template parameters aren’t required to be types.

This only works when T is an integral type (int, unsigned, long, char etc but not float, std::string, const char*, etc), as @Riga mentioned in his/her comment.