Question

What guidelines do you follow to improve the general quality of your code? Many people have rules about how to write C++ code that (supposedly) make it harder to make mistakes. I’ve seen people insist that every if statement is followed by a brace block ({...}).

I’m interested in what guidelines other people follow, and the reasons behind them. I’m also interested in guidelines that you think are rubbish, but are commonly held. Can anyone suggest a few?

To get the ball rolling, I’ll mention a few to start with:

• Always use braces after every if / else statement (mentioned above). The rationale behind this is that it’s not always easy to tell if a single statement is actually one statement, or a preprocessor macro that expands to more than one statement, so this code would break:

     // top of file:     #define statement doSomething(); doSomethingElse      // in implementation:     if (somecondition)         doSomething(); 

but if you use braces then it will work as expected.

• Use preprocessor macros for conditional compilation ONLY. preprocessor macros can cause all sorts of hell, since they don’t allow C++ scoping rules. I’ve run aground many times due to preprocessor macros with common names in header files. If you’re not careful you can cause all sorts of havoc!

Now over to you.

Answer 1

A few of my personal favorites:

Strive to write code that is const correct. You will enlist the compiler to help weed out easy to fix but sometimes painful bugs. Your code will also tell a story of what you had in mind at the time you wrote it — valuable for newcomers or maintainers once you’re gone.

Get out of the memory management business. Learn to use smart pointers: std::auto_ptr, std::tr1::shared_ptr (or boost::shared_ptr) and boost::scoped_ptr. Learn the differences between them and when to use one vs. another.

You’re probably going to be using the Standard Template Library. Read the Josuttis book. Don’t just stop after the first few chapters on containers thinking that you know the STL. Push through to the good stuff: algorithms and function objects.