Advanced C++ Programming Cookbook

How it works...

Before C++17, you could provide non-type template arguments in a template, but you had to state the variable type in the definition, as shown in this example:

#include <iostream>template<int answer>void foo(){    std::cout << "The answer is: " << answer << '\n';}int main(void){    foo<42>();    return 0;}

The output is as follows:

In the preceding example, we create a template argument variable of the int type and output the value of this variable to stdout. In C++17, we can now do the following:

#include <iostream>template<auto answer>void foo(){    std::cout << "The answer is: " << answer << '\n';}int main(void){    foo<42>(); return 0; ...