Gain insights into using Modern C++ for embedded programming. Learn about safety-critical systems, optimize performance, manage limited resources, and handle parallel execution effectively.

waleed1.tar.gz

C++11

C++ 17

Embedded Programming with Modern C++  is highly valuable for each professional programmer.

In the past, embedded and system programming have had their pitfalls, but modern C++ has been designed to be a better language for this type of development, addressing the previous pitfalls/requirements explicitly. What are these requirements? Embedded systems deal with safety-critical systems, meaning they must guarantee high performance combined with limited resources, while also working in parallel.

The scope of this course goes beyond just embedded programming. Developers who write servers, games, or trading systems may especially benefit from this course because they also have to deal with safety-critical systems, high performance, reduced resources, and parallel execution in their jobs.

To get the most out of the course, you only need a basic understanding of C++. Building off this understanding, this course goes over all the essentials of embedded programming with Modern C++.

Let's get started!

Embedded Programming with Modern C++

// weakPtr.cpp

#include <iostream>
#include <memory>

int main(){

  std::cout << std::boolalpha << std::endl;

  auto sharedPtr=std::make_shared<int>(2011);
  std::weak_ptr<int> weakPtr(sharedPtr);
  
  std::cout << "weakPtr.use_count(): " << weakPtr.use_count() << std::endl;
  std::cout << "sharedPtr.use_count(): " << sharedPtr.use_count() << std::endl;
  std::cout << "weakPtr.expired(): " << weakPtr.expired() << std::endl;

  if( std::shared_ptr<int> sharedPtr1 = weakPtr.lock() ) {
    std::cout << "*sharedPtr: " << *sharedPtr << std::endl;
    std::cout << "sharedPtr1.use_count(): " << sharedPtr1.use_count() << std::endl;
  }
  else{
    std::cout << "Don't get the resource!" << std::endl;
  }

  weakPtr.reset();
  if( std::shared_ptr<int> sharedPtr1 = weakPtr.lock() ) {
    std::cout << "*sharedPtr: " << *sharedPtr << std::endl;
    std::cout << "sharedPtr1.use_count(): " << sharedPtr1.use_count() << std::endl;
  }
  else{
    std::cout << "Don't get the resource!" << std::endl;
  }

  std::cout << std::endl;

}

## Explanation
* In line 11, we create a `std::weak_ptr` that borrows the resource from the `std::shared_ptr`. 

* The output of the program shows that the reference counter is 1 (line 13 and 14), meaning that `std::weak` does not increment the counter.

* The call `weakPtr.expired()` checks if the resource was already deleted. That is equivalent to the expression `weakPtr.use_count() == 0`. 

* If the `std::weak_ptr` shared a resource, you can use `weakPtr.lock()` to create a `std::shared_ptr` out of it. 

* The reference counter will now be increased to 2 (line 18). After resetting the `weakPtr` (line 25), the call `weakPtr.lock()` fails.

That was almost the whole story for the `std::weak_ptr`. Almost, because the `std::weak_ptr` has a special job: it helps to break the [cyclic references](https://www.educative.io/courses/embedded-programming-with-cpp/smart-pointers-cyclic-references) of `std::shared_ptr`.



As compared to the std::shared_ptr, std::weak_ptr does not change the reference counter of the shared variable. Let's take a look at that feature in the example below.

Introduction

Safety-Critical Systems

High Performance

Reduced Resources

Several Tasks Simultaneously

Conclusion

- Example