C++ (Core) Coding Guidelines

Table of Contents

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:

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

https://wiki.qt.io/Coding_Conventions

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
C++ Coding Standards: 101 Rules, Guidelines, and Best Practices, from 2004, but still contains some useful tips.

Blog posts

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.

What guideline I am missing here? Let me know if you have a useful link to that.

What coding guideline do you use? Company internal? Or some open guideline?
Do you obey the rules from your guideline?
Do you use auto format tools?