Short-hands and Shortcuts of C/C++

Question

Are there any resources out there that sort of describe much of the short-hand methods that C and C++ have to offer? There's alot of "wild" code out there that does not exactly mesh up with what is taught in text books. For example, many of text books teach you to separate the declaration and initialization of variables, yet I see the contrary happen all the time.

So here is my current stumper: Does C allow procedures without a type identifier? Again, text books tell me that I should at very least you a void type if no other type is indicated. However, I have seen the following:

procedure(){
//procedure stuff
}

where otherwise I have always been taught you must at least do

void procedure(){
//procedure stuff
}

I find myself in this position alot and I think its a symptom of not had exposure to project/team related work in C or C++. I have a hard time identifying "compilable code" because many books teach a specific way, but there's more than one way to accomplish the same task in practice. Thanks.

Answer 1

Omitting the return type in a function definition makes the function implicitly returns int in C89. Since C99 this is no longer accepted and the implementation could refuse to translate a program with a function definition that omits the return type.

From C99 Rationale document:

In C89, all type specifiers could be omitted from the declaration specifiers in a declaration. In such a case int was implied. The Committee decided that the inherent danger of this feature outweighed its convenience, and so it was removed.

Answer 2

If there is no explicit return type, it is assumed to be int. It is there for legacy reasons.

Another legacy compatibility thing is you can omit argument types, too:

add(a, b) { // a and b implicitly int
    return a + b;
}

Or you can declare the types of arguments... differently...

strlen2(s)
const char *s;
{
    int l = 0;
    while(*s++) l++;
    return l;
}

I wouldn't leverage any of these features in new code, though, obviously.

Answer 3

I think you are referring to the parameters. In that case it is a good to use void if no parameters are passed however it is not required, although then it has unknown amount of arguments