What are the most common naming conventions in C?

Question

Hi,

What are the naming conventions commonly use in C? I know there are at least two:

1. GNU / linux / K&R with lower_case_functions
2. ? name ? with UpperCaseFoo functions

I am talking about C only here. Most of our projects are small embedded systems in which we use C.

Here is the one I am planning on using for my next project:

---

C Naming Convention

Struct   TitleCase
Struct Members  lower_case or lowerCase

Enum     ETitleCase
Enum Members    ALL_CAPS or lowerCase

Public functions    pfx_TitleCase (pfx = two or three letter module prefix)
Private functions   TitleCase
Trivial variables   i,x,n,f etc...
Local variables lower_case or lowerCase
Global variables    g_lowerCase or g_lower_case (searchable by g_ prefix)

Answer 1

"Struct pointers" aren't entities that need a naming convention clause to cover them. They're just struct WhatEver *. DON'T hide the fact that there is a pointer involved with a clever and "obvious" typedef. It serves no purpose, is longer to type, and destroys the balance between declaration and access.

Answer 2

Well firstly C doesn't have public/private/virtual functions. That's C++ and it has different conventions. In C typically you have:

• Constants in ALL_CAPS
• Underscores to delimit words in structs or function names, hardly ever do you see camel case in C;
• structs, typedefs, unions, members (of unions and structs) and enum values typically are in lower case (in my experience) rather than the C++/Java/C#/etc convention of making the first letter a capital but I guess it's possible in C too.

C++ is more complex. I've seen a real mix here. Camel case for class names or lowercase+underscores (camel case is more common in my experience). Structs are used rarely (and typically because a library requires them, otherwise you'd use classes).

Answer 3

I would recommend against mixing camel case and underscore separation (like you proposed for struct members). This is confusing. You'd think, hey I have get_length so I should probably have make_subset and then you find out it's actually makeSubset. Use the principle of least astonishment, and be consistent.

I do find CamelCase useful to type names, like structs, typedefs and enums. That's about all, though. For all the rest (function names, struct member names, etc.) I use underscore_separation.

Answer 4

The most important thing here is consistency. That said, I follow the GTK+ coding convention, which can be summarized as follows:

1. All macros and constants in caps: MAX_BUFFER_SIZE, TRACKING_ID_PREFIX.
2. Struct names and typedef's in camelcase: GtkWidget, TrackingOrder.
3. Functions that operate on structs: classic C style: gtk_widget_show(), tracking_order_process().
4. Pointers: nothing fancy here: GtkWidget *foo, TrackingOrder *bar.
5. Global variables: just don't use global variables. They are evil.
6. Functions that are there, but shouldn't be called directly, or have obscure uses, or whatever: one or more underscores at the beginning: _refrobnicate_data_tables(), _destroy_cache().

Answer 5

I'm confused by one thing: You're planning to create a new naming convention for a new project. Generally you should have a naming convention that is company- or team-wide. If you already have projects that have any form of naming convention, you should not change the convention for a new project. If the convention above is just codification of your existing practices, then you are golden. The more it differs from existing de facto standards the harder it will be to gain mindshare in the new standard.

About the only suggestion I would add is I've taken a liking to _t at the end of types in the style of uint32_t and size_t. It's very C-ish to me although some might complain it's just "reverse" Hungarian.

Answer 6

Here's an (apparently) uncommon one, which I've found useful: module name in CamelCase, then an underscore, then function or file-scope name in CamelCase. So for example:

Bluetooth_Init()
CommsHub_Update()
Serial_TxBuffer[]