C++ (Core) Coding Guidelines

Since 2011, when C++11 arrived, we all should be changing our coding style into modern C++ and at the same time keep good old tips. There are also general rules for programming and bug-free coding. Here’s a list of guidelines and other resources that might help you.

Core C++ Guidelines

Main site: C++ Core Guidelines

From the abstract:

This document is a set of guidelines for using C++ well. The aim of 
this document is to help people to use modern C++ effectively. By 
“modern C++” we mean C++11 and C++14 (and soon C++17). In other words, what would you like your code to look like in 5 years’ time, given that you can start now? In 10 years’ time?

Elements:

• In: Introduction
• P: Philosophy
• I: Interfaces
• F: Functions
• C: Classes and class hierarchies
• Enum: Enumerations
• R: Resource management
• ES: Expressions and statements
• E: Error handling
• Con: Constants and immutability
• T: Templates and generic programming
• CP: Concurrency
• STL: The Standard library
• SF: Source files
• CPL: C-style programming
• PRO: Profiles
• GSL: Guideline support library
• FAQ: Answers to frequently asked questions
• NL: Naming and layout
• PER: Performance
• N: Non-Rules and myths
• RF: References
• Appendix A: Libraries
• Appendix B: Modernizing code
• Appendix C: Discussion

The guideline is moderated by Bjarne Stroustrup and Herb Sutter. Here’s Bjarne Stroustrup’s C++ Style and Technique FAQ and Sutter’s GotW section.

Additionally here’s the post from Kate Gregory about coding guidelines: C++ Core Guidelines and Checking Tool And also, she started doing more posts about core guidelines, for example: Using the not_null Template for Pointers That Must Never Be Null

Learn From Bugs

Some time ago a company that produces PVS-Studio for C/C++/C# (viva64.com/) posted a very long list of potential bugs and tips that you can use to improve your C++ code. It’s also in the form of a book:

The book covers 42 topics. In spite of the simple titles of the chapters, the bugs found are really various and non-standard. In addition to that, the text provides a lot of links to interesting materials that give more details on topics. To make more use of this book, please don’t hurry and go to the links provided.

Content:

1. Don't do the compiler's job
2. Larger than 0 does not mean 1
3. Copy once, check twice
4. Beware of the ?: operator and enclose it in parentheses
5. Use available tools to analyze your code
6. Check all the fragments where a pointer is explicitly cast to integer types
7. Do not call the alloca() function inside loops
8. Remember that an exception in the destructor is dangerous.
9. Use the '\0' literal for the terminal null character
10. Avoid using multiple small #ifdef blocks
11. Don't try to squeeze as many operations as possible in one line
12. When using Copy-Paste, be especially careful with the last lines
13. Table-style formatting
14. A good compiler and coding style aren't always enough
15. Start using enum class in your code, if possible
16. "Look what I can do!" - Unacceptable in programming
17. Use dedicated functions to clear private data
18. The knowledge you have, working with one language isn't always applicable to another language
19. How to properly call one constructor from another
20. The End-of- file (EOF) check may not be enough
21. Check that the end-of- file character is reached correctly (EOF)
22. Do not use #pragma warning(default:X)
23. Evaluate the string literal length automatically
24. Override and final identifiers should become your new friends.
25. Do not compare 'this' to nullptr anymore
26. Insidious VARIANT_BOOL
27. Guileful BSTR strings
28. Avoid using a macro if you can use a simple function
29. Use a prefix increment operator (++i) in iterators instead of a postfix (i++) operator
30. Visual C++ and wprintf() function
31. In C and C++ arrays are not passed by value
32. Dangerous printf
33. Never dereference null pointers
34. Undefined behavior is closer than you think
35. Adding a new constant to enum don't forget to correct switch operators
36. If something strange is happening to your PC, check its memory.
37. Beware of the 'continue' operator inside do {…} while (…)
38. Use nullptr instead of NULL from now on
39. Why incorrect code works
40. Start using static code analysis
41. Avoid adding a new library to the project.
42. Don't use function names with "empty"

Here’s the post: http://www.viva64.com/en/b/0391/ that gets regularly updated. I highly encourage you to read about those problems from time to time… maybe something similar could be improved in your apps?

Google Coding Standard

Google C++ Coding Standard is another popular resource that is public and easy to find

Just go here: https://google.github.io/styleguide/cppguide.html

Top level index:

• Header Files
• Scoping
• Classes
• Functions
• Google-Specific Magic
• Other C++ Features
• Naming
• Comments
• Formatting
• Exceptions to the Rules
• Existing Non-conformant CodeWindows Code

Since Google is a software giant, we should obey their rules, right? Not that easy! There is a huge discussion going on if the guide is good or not. Read especially this detailed post: Why Google Style Guide for C++ is a deal-breaker. And here is a Reddit thread for the article.

What are the main controversies over the guide: banning exceptions, public inheritance, passing reference parameters, probably not using advanced template techniques.

To see reasoning behind the guideline, you can watch this video:

CppCon 2014: Titus Winters “The Philosophy of Google’s C++ Code”

Other Guidelines

Bloomberg - BDE

https://github.com/bloomberg/bde/wiki/Introduction-to-BDE-Coding-Standards

OpenOffice

http://www.openoffice.org/tools/coding.html

LLVM

http://llvm.org/docs/CodingStandards.html

Mozilla

https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Coding_Style

Chrominium

https://www.chromium.org/developers/coding-style

Mostly it uses Google Style Guide, but here are also some specific sections: C++11 use in Chromium or C++ Dos and Don’ts

High Integrity C++ Coding Standard Version

http://www.codingstandard.com/

WebKit

https://webkit.org/code-style-guidelines/

ROS (Robot Operating System)

http://wiki.ros.org/CppStyleGuide

They have also invested in auto format tool: roscpp Code Format

SEI CERT C++ Coding Standard

www.securecoding.cert.org

Little Bonus:

• Linux Kernel Guideline C language - @kernel.org
• NASA JPL Guideline - C language, PDF - PDF guideline and the reddit discussion.

Books

• Effective C++ series from Scott Meyers 
  • Effective Modern C++: 42 Specific Ways to Improve Your Use of C++11 and C++14
  • Effective C++: 55 Specific Ways to Improve Your Programs and Designs
  • Effective STL: 50 Specific Ways to Improve Your Use of the Standard Template Library
• C++ Coding Standards: 101 Rules, Guidelines, and Best Practices, from 2004, but still contains some useful tips.

Blog Posts

• Richard Rodger: Why I Have Given Up on Coding Standards
• CodeAhoy: Effective Coding Standards
• Paul M. Jones: Why Coding Standards Matter

Summary

In this post, I brought you a list of C++ guidelines that might add value to your internal guidelines. Please have a look especially at C++ Core Guidelines since it’s created by the community and moderated by Bjarne Stroustrup and Herb Sutter.