Where can I find resources about "modern" C programming? [closed]

Question

In spite of having read K&R, and having even taught C classes, I find myself embarrassingly unable to fully understand what one might call "modern" C.

There seems to be many unwritten conventions in modern programming that, as far as I know, aren't documented anywhere.

Take, for example, the SQLite source code. In it I find for instance:

 SQLITE_API int sqlite3_close(sqlite3 *);

What does SQLITE_API stand for? How is this even syntactically correct?

Or this:

#ifndef _SQLITE3_H_
#define _SQLITE3_H_

Is there an accepted convention somewhere on when to prefix macros with underscores? Sometimes I see macros prefixed with two underscores.

Or what about the use of fixed-size types, such as uint32 and so forth. When should one use this practice, and when not? What about the new-ish bool type, when should it be preferred over simple ints?

These are some of the questions I pose myself when I read other people's source code. Is there a reference somewhere that might help me answer these questions?

Answer 1

SQLITE_API in code like this is very likely a preprocessor define, that worries about exposing the call in e.g. a DLL library build. That's pretty common.

If it's all upper case in C, chances are it's a preprocessor symbol, and a good idea is often to run the game through the preprocessor and read what comes out.

Answer 2

Afaik GNU coding standards are under constant revision/update so might be a good snapshot of 'modern' style.

http://www.gnu.org/prep/standards/

Re: specifically single or double undercores, in my experience and from what I often read; it's grossly accepted safer to avoid double underscore prefixes as these are usually 'reserved' for framework/system/compiler-specific and compiler-related elements, thus macros intended soley for use within the module/package/unit/project they are defined should avoid being undescore-prefixed at all.

Most institions have their own language coding standards and guidelines which can vary quite significantly. As ever, consistency is key.