Introduction to C++20

C++ has evolved over the years and now it has a brand-new version, C++20. Since C++11, the C++ standard has grown the language feature set tremendously. Let's look at notable features in the new C++20 standard.

Concepts

Concepts are a major feature in C++20 that provides a set of requirements for types. The basic idea behind concepts is the compile-time validation of template arguments. For example, to specify that the template argument must have a default constructor, we use the default_constructible concept in the following way:

template <default_constructible T>
void make_T() { return T(); }

In the preceding code, we missed the typename keyword. Instead, we set a concept that describes the...