Google C++ Style Guide suggests
Return type on the same line as function name, parameters on the same line if they fit.
Functions look like this:
ReturnType ClassName::FunctionName(Type par_name1, Type par_name2) {
DoSomething();
...
}
WebKit Coding Style Guidelines suggests
Function definitions: place each brace on its own line.
Right:
int main()
{
...
}
Wrong:
int main() {
...
}
They suggest braces-on-same-line for everything else, though.
GNU Coding Standards suggests
It is important to put the open-brace that starts the body of a C function in column one, so that they will start a defun. Several tools look for open-braces in column one to find the beginnings of C functions. These tools will not work on code not formatted that way.
Avoid putting open-brace, open-parenthesis or open-bracket in column one when they are inside a function, so that they won't start a defun. The open-brace that starts a struct body can go in column one if you find it useful to treat that definition as a defun.
It is also important for function definitions to start the name of the function in column one. This helps people to search for function definitions, and may also help certain tools recognize them. Thus, using Standard C syntax, the format is this:
static char *
concat (char *s1, char *s2)
{
...
}
or, if you want to use traditional C syntax, format the definition like this:
static char *
concat (s1, s2) /* Name starts in column one here */
char *s1, *s2;
{ /* Open brace in column one here */
...
}
As you can see, everybody has their own opinions. Personally, I prefer the Perl-ish braces-on-same-line-except-for-else, but as long as everybody working on the code can cooperate, it really doesn't matter.
