Whats new in C++

 As of my knowledge cutoff in September 2021, the latest major version of C++ is C++20. C++20 introduced several new features and enhancements to the language. Here are some notable additions:

1. Modules: C++20 introduced a new module system to replace the traditional header files. Modules improve compilation times, reduce dependencies, and provide better encapsulation of code.

2. Concepts: Concepts allow specifying requirements on template arguments, enabling more precise type checking and better documentation of template interfaces. They help improve template code readability and enable more effective error messages.

3. Ranges: C++20 introduced the Ranges library, which provides a more modern and concise approach to working with sequences of elements. It offers a new set of algorithms and range adaptors that make working with containers and ranges easier and more expressive.

4. Coroutines: Coroutines are a new way of writing asynchronous code in a more sequential and readable manner. They provide a way to pause and resume execution at specific points and are useful for tasks involving asynchronous I/O, generators, and state machines.

5. Three-Way Comparisons: C++20 introduced the spaceship operator (`<=>`) and support for three-way comparisons. It allows for a more concise and expressive way to compare objects, simplifying the implementation of comparison operations.

6. New Standard Attributes: C++20 added several new standard attributes, including likely/unlikely, fallthrough, nodiscard, and deprecated, which provide standardized ways to convey specific intentions to the compiler and improve code clarity.

7. Improved constexpr: C++20 expanded the capabilities of `constexpr`, allowing more functions and variables to be evaluated at compile-time. This helps in optimizing performance and enables more compile-time computations.

8. Improved `std::span`: C++20 enhanced the `std::span` class template, which provides a non-owning reference to a sequence of elements. The improvements include better compatibility with containers and support for multidimensional arrays.

9. Calendar and Time Zone: C++20 added support for working with calendars, dates, and time zones. It introduced new classes and functions in the `<chrono>` library to handle dates, times, durations, and time zones more effectively.

Please note that C++ continues to evolve, and new features may be introduced in future versions. It's always a good practice to refer to the official C++ standards documentation and stay updated with the latest developments in the language.