Understanding the Differences Between C11, C14, and C17 Through Practice: A Comprehensive Guide

With every new release of the C programming language, there are always new changes that can be categorized into two main sections: changes in the libraries and changes in the core language. While libraries changes are usually focused on the addition of new features to the standard library, core language changes often cover a wide range of improvements and new features such as support for multithreading, generic programming, uniform initialization, and performance optimizations.

For instance, the standard library of C has several new features introduced in different C versions, such as std::atomic, std::thread, and std::optional. These features significantly enhance the functionality and efficiency of the language. On the other hand, the core language changes include additions like 'noexcept' for exception specifications, 'constexpr' for compile-time computation, and 'Concepts' (from C 20 onward) for type constraints. These core language changes are critical for writing more robust and efficient code.

Practical Approach to Learning the Differences

The best way to understand these differences is by working through the changes yourself. You can start by exploring the CXX specific information on or through C reference pages for each version. This will give you a detailed understanding of what has been added or deprecated in each version.

Most importantly, trying to write code using the latest practices, even if you are working with an older version of the language, will help you gain a deeper understanding of how newer features can be used and when to apply them. As you encounter specific versions without certain features you’ve come to rely on, you will naturally develop a kind of situational awareness that will help you adapt.

Summary of Key Features

The following are some of the key features introduced in C11, C14, and C17 versions:

C11

Support for OpenMP and multithreading Declarations and static initializers in struct/enum/union/typedef for structure layout Shortened 'if' statements with {} (known as the 'herly braces' syntax)

C14 added no specific version-specific features, but continued to refine the language with minor improvements and bug fixes, mainly focusing on performance and standard library enhancements.

C17

Finalization support in struct initialization Nominal types Additional support for variable-length arrays (VLAs) Immersive mode for assertions Defining const variables at file scope

Overall, moving incrementally through each version, you'll see a progression of new features and improvements. It's recommended to focus on modern practices and let situational awareness develop organically as you encounter limitations in older versions.

Practical Steps for a Modern Approach

As you learn and practice with the latest version of C, you will eventually reach a point where you can appreciate the full range of features and make informed decisions about their usage. Here are some practical steps you can take:

Explore the differences between versions through online resources like and C reference pages. Understand prerequisite concepts before attempting to learn more advanced features. For instance, noexcept requires a basic understanding of exception handling in C 20, concepts require familiarity with generic programming and templates, and rvalue references bring more depth to understanding overload resolution in C 11. Check out Jason Turner’s YouTube channel and his series on “CWeekly” to see examples of how these features are used in practice.

By embracing a practical and incremental approach to learning, you can fully understand and appreciate the differences between C11, C14, and C17. Remember, the goal is not to memorize the differences but to develop the ability to write efficient and effective code in each version.