Explore the power of C++ templates, from function and class basics to advanced features like instantiation and concepts, enhancing code flexibility, reusability, and abstraction without performance loss.

cpp17.tar.gz

C++17

C++20

Templates are one of the many powerful features of Modern C++ programming. And with each new C++ standard, they become more important. 

Templates provide an efficient way to make your code more flexible and reusable, this way you can avoid repeating code that would otherwise be identical except for different types. Templates also give you the ability to provide abstraction without a performance penalty.

However, templates can be difficult to apply, can be counterintuitive, and have tricky error messages.

This course gives you the necessary information to overcome these hurdles and dive into the advanced topics. You’ll visit the basics such as function and class templates, and then explore the details to templates such as instantiation and fold expressions. Our journey also includes techniques based on templates, the design, and future directions of templates such as concepts. Based on this exhaustive tour of templates, a basic understanding of C++ is sufficient to master this course.

Let’s get started!

Generic Programming Templates in C++

#include <cstddef>
#include <iostream>
#include <typeinfo>

template <char c>
class AcceptChar{
public:
  AcceptChar(){
    std::cout << "AcceptChar: "  << typeid(c).name() << std::endl;
  }
};

template < int(*func)(int) >
class AcceptFunction{
public:
  AcceptFunction(){
    std::cout << "AcceptFunction: "  << typeid(func).name() << std::endl;
  }
};

template < int(&arr)[5] >
class AcceptReference{
public:
  AcceptReference(){
    std::cout << "AcceptReference: " << typeid(arr).name() << std::endl;
  }
};

template < std::nullptr_t N >
class AcceptNullptr{
public:
  AcceptNullptr(){
    std::cout << "AcceptNullpt: " << typeid(N).name() << std::endl;
  }
};

int myFunc(int){ return 2011; };
int arr[5];

int main(){

  std::cout << std::endl;

  AcceptChar<'c'> acceptChar;
  AcceptFunction< myFunc> acceptFunction;
  AcceptReference< arr > acceptReference;
  AcceptNullptr< nullptr > acceptNullptr;

  std::cout << std::endl;

}


## Explanation

We have created four different class templates which include `AcceptChar`, `AcceptFunction`, `AcceptReference`, and `AcceptNull` in lines 6, 14, 22, and 30. Each class template accepts a different non-type. To verify all, we have declared a *character* variable, a *reference* to an array, a function, and `nullptr` in lines 44 -- 47. This matches the order of declaration in the code.
 We identify their type using the operator `typeid` in lines 9, 17, 25, and 33.  

In this lesson, we'll look at the solution review of the previous challenge.

Introduction

Basics

Details

Techniques

Design

Future

Conclusion

- Solution

Solution Review