C++ Standards and Implementations

C++ programming language is widely used and known for its power, versatility, and performance. C++ is an extension of the C programming language created by Danish computer scientist Bjarne Stroustrup. With time several C++ standards have been introduced with new features and enhancements. In this article, we will explore the major C++ standards, along with their key features to understand the evolution of C++ and the benefits provided to programmers or developers.

Nowadays C++ is popular for competitive programming because of its performance but it is also used for building robust applications which we are using in our daily life. A few of them are given below:

• Operating Systems
• Games
• Embedded Systems
• Compilers
• Web Browsers

What are C++ Standards and why do we need them?

C++ standards are maintained by the International Organization for Standardization (ISO) and the C++ committee. They define the rules and features such as syntax and behavior of the C++ programming language. Each standard, such as C++98, C++11, C++17, and so on, introduces new language features, libraries, and improvements while maintaining backward compatibility with previous versions.

If the C++ programming language is not standardized then we have to face lots of problems like compatibility of C++ programs in various systems. Different programmers have their own rules and syntax and cannot able to understand the codes of other programmers. so, it is important to establish an organization that can maintain and regulate C++ standards which would be followed by all the programmers in the world.

Major C++ Standards Released

• C++98
• C++11
• C++14
• C++17
• C++20

C++98

C++98 is the first and original version of C++ programming language released in 1998 which is also known as C++03. This is very similar to C language with added features.

Key features of the C++98 standard are:

• Classes: The ability to define classes and objects. Classes provide robust OOPs features which include Inheritance, Encapsulation, Abstraction, and Polymorphism.
• Templates: It is similar to a function with additional features of passing data type along with parameters. For example, writing the sort() function for different data types.
• Exception Handling: A robust error-handling mechanism to handle exceptional conditions during program execution using the try, catch, and throw keywords.
• STL: Standard Template Library is the collection of generic algorithms, containers, and iterators that simplifies common programming tasks.
• Namespaces: Namespaces were introduced in C++98 to help in organizing code and prevent any naming conflicts.

C++11

C++11 released in 2011, comes with notable features such as Lambda expressions, the auto keyword, range-based for loops, nullptr, and smart pointers (unique_ptr, shared_ptr). With the introduction of the thread library, C++11 also enhanced multithreading capabilities.

Key features of the C++11 standard are:

• Lambda Expressions: These are Anonymous functions that can be used inline. We use Lambda Expressions when we need to write a few lines of code that won’t be used again.
• Auto Keyword: Automatic type inference deduces the data type of an expression automatically which can improve readability.
• Multithreading: The introduction of the thread library for concurrent and parallel programming so that the CPU can be utilized efficiently.
• Range-Based For Loops: Simplified iteration over elements of a container or sequence.
• Smart Pointers: Smart pointers include Unique_ptr, shared_ptr, and weak_ptr which automatically deallocates the memory allocated in the heap so that it can be reused. It provides safer and more efficient memory management.
• Hashing Data Structure: We can store data in the form of key and value pair in the Hash Table.
• Move Semantics: Move semantics is a feature in C++11 that enhances the efficiency of transferring resources between objects.

C++14

C++14 was released in 2014. The motive for releasing C++14 was to make the improvement that was left or not done in C++11 to make it a cleaner and faster language.

Key features of C++14 features are:

• Improved Template Aliases: Simplified syntax for defining type aliases using the using keyword.
• Binary Literals: The ability to represent integral values in binary form for improved readability.
• Relaxed constexpr: Relaxed constexpr relaxes some of the limitations of the constexpr that makes it more flexible.
• Generic Lambdas: C++14 allows the lambda to be used with the auto keyword as the parameter type in the parameter list as generic parameters.
• Return type deduction for functions: The normal functions can be used with the “auto” keyword as their return type which can automatically deduce their return type.

C++17

C++17 is released in 2017 with additional features which are not present in C++14 and also with improved features of C++14 which is constexpr. Key features of the C++17 standard are as follows:

• Structured Bindings: The ability to decompose structured objects into individual variables easily.
• if constexpr: This is a new feature introduced in C++ 17 that allows us to write conditional statements that are evaluated at the compile time.
• Fold Expressions: A concise syntax for expanding variadic templates and applying operators to template arguments.
• Parallel Algorithms in the STL: Standardized parallel algorithms for efficient execution on multi-core systems.
• Inline Variables: Inline variables can be defined in multiple translation units without violating the One Definition Rule (ODR).
• CTAD: This is the feature introduced in C++17 that is used to deduce template arguments for a class template from its constructor arguments.
• Nested Namespaces: In C++17 we can create namespaces within other namespaces.
• Variable declaration in if and switch: In C++17, we can declare and initialize variables directly within if and switch statements.

C++20

C++20 was released in 2020 with new features that enhance the performance of the code in terms of compilation time, reusability, and concurrency.

Key features of the C++20 standard are:

• Concepts Library: It is defined in the <concepts> header file and used to define the requirements on template arguments, allowing more shorter and understandable code.
• Ranges: It is a new library that helps programmers to work with sequences, providing a more expressive and efficient alternative to iterators.
• Coroutines: They can help in achieving concurrency while implementing asynchronous code.
• Three-Way Comparisons: It is also called spaceship operator. It is used to compare two objects whether they are equal, greater than, or less than each other. The three-way comparison operator expression is of the form lhs <=> rhs.
• Modules: A new way to organize and manage code, improving compilation times and enhancing code isolation and reusability.
• Calendar and time zone library: It is defined in <chrono> header file that provides a detailed way to represent date and time and work efficiently with date and time and different time zones.
• std::to_array: It is used to convert a C-style array or list to std::array.

C++23

C++23 is the next version of C++ which is going to release in December 2023. In this standard, some of the features of C++ are eliminated with the introduction of new features.

Some of the new features introduced in this standard are:

• static operator[]: This feature is used to access the operator[] on multidimensional arrays and on static arrays which makes the accessing of array elements easier.
• static constexpr in constexpr functions: This feature can be used to use constexpr variables within constexpr functions.
• std::print: Now in C++23, output of std::print has been synchronized with data outputs.
• Monadic interface for std::expected: It is similar to the monadic interface that already exists for std::optional and is now also included for std::expected.