C++11

The C++ programming language is a very powerful tool and has really great performance, but it is also really complex, even after years of practice. It allows us to program at both a low and high level. It's useful to make some optimizations on our program such as having the ability to directly manipulate memory. Building software utilizing C++ libraries allows us to work at a higher level and when performance is crucial, at a low level. Moreover, the C/C++ compilers are very efficient at optimizing code. The result is that, right now, C++ is the most powerful language in terms of speed, and thanks to the zero cost abstraction, you are not paying for what you don't use, or for the abstraction you are provided.

I'll try to use this language in a modern way, using the object-oriented approach. Sometimes, I'll bypass this approach to use the C way for optimizations. So do not be shocked to see some "old school code". Moreover, all the main compilers now support the standard language released in 2011, so we can use it everywhere without any trouble. This version adds some really useful features in the language that will be used in this book, such as the following:

• Keywords are one such important feature. The following are a few of them:
  • auto: This automatically detects the type of the new variable. It is really useful for the instantiation of iterators. The auto keyword already existed in the past, but has been deprecated for a long time, and its meaning has now changed.
  • nullptr: This is a new keyword introducing a strong type for the old NULL value. You can always use NULL, but it's preferable to use nullptr, which is any pointer type with 0 as the value.
  • override and final: These two keywords already exist in some languages such as Java. These are simple indications not only for the compiler but also for the programmer, but don't specify what they indicate. Don't hesitate to use them. You can take a look to the documentation of them here http://en.cppreference.com/w/cpp/language/override and http://en.cppreference.com/w/cpp/language/final.
• The range-based for loops is a new kind of loop in the language foreach. Moreover, you can use the new auto keyword to reduce your code drastically. The following syntax is very simple:

  for(auto& var : table){...}.

  In this example, table is a container (vector and list) and var is a reference to the stored variable. Using & allows us to modify the variable contained inside the table and avoids copies.

• C++11 introduces the smart pointers. There are multiple pointers corresponding to their different possible utilizations. Take a look at the official documentation, this which is really interesting. The main idea is to manage the memory and delete the object created at runtime when no more reference on it exists, so that you do not have to delete it yourself or ensure that no double free corruptions are made. A smart pointer created on the stack has the advantages of being both fast and automatically deleted when the method / code block ends. But it is important to know that a strong use of this pointer, more especially shared_ptr, will reduce the execution speed of your program, so use them carefully.
• The lambda expression or anonymous function is a new type introduced with a particular syntax. You can now create functions, for example, as a parameter of another function. This is really useful for callback. In the past, functor was used to achieve this kind of comportment. An example of functor and lambda is as follows:

  class Func(){ void operator()(){/* code here */}};
  auto f = [](){/* code here*/};

• If you already know the use of the variadics function with the ellipse operator (...), this notion should trouble you, as the usage of it is different. The variadics template is just the amelioration of template with any number of parameters using the ellipse operator. A good example for this is the tuple class. A tuple contains any number of values of any type known at compile time. Without the variadics template, it was not really possible to build this class, but now it is really easy. By the way, the tuple class was introduced in C++11. There are several other features, such as threads, pair, and so on.