In C++, variadic templates allow you to define functions or classes that can take an arbitrary number of arguments of different types. This powerful feature comes in handy when dealing with functions or classes that need to be flexible and adaptable. One common use case is when you want to process or operate on each argument individually. To do this, you can use recursive templates.

Recursive templates allow you to create a template that handles the first argument and then calls itself with the remaining arguments until all arguments have been processed. This recursive approach is useful when you need to perform a similar operation on each argument in a variadic parameter pack.

Let’s illustrate this concept with an example: a print function that can print any number of arguments.

template <typename T>
void print(T arg) {
    std::cout << arg << std::endl;
}

template <typename T, typename... Args>
void print(T arg, Args... args) {
    std::cout << arg << ", ";
    print(args...);
}

In this example, the first print function is the base case that handles the last argument in the pack. It simply prints the argument and ends the recursion.

The second print function takes the first argument (arg) and prints it, then calls itself with the remaining arguments (args...). This recursive call continues until all arguments in the pack have been processed.

You can use this print function like this:

int main() {
    print(1, 2, 3, "four", 5.5);
    return 0;
}

The output will be:

1, 2, 3, four, 5.5

The recursive template approach allows you to write generic code that can handle any number and any type of arguments. Whether it’s printing values, performing calculations, or any other operation, recursive templates provide a powerful mechanism for working with variadic template parameters in C++.

#cpp #templates