How to use library?

Actually, that is real 'C'

Unless advised otherwise (eg, by a function prototype) 'C' assumes that all functions return int and take no parameters [1].

Therefore you can call library functions without specifying a prototype provided that they take no parameters and the return value is either not used, or is assignment-compatible with 'int'.

You must provide a prototype if you want your library function to take any parameters, or you'll get error C267, "requires ANSI-style prototype"

But it's always good practice to provide function prototypes, as this gives the compiler the chance to warn you of type mismatches.

[1] kernighan & Ritchie
"The C Programming Language, 2/ed"
Prentice-Hall, 1988.

Actually, that is real 'C'

Unless advised otherwise (eg, by a function prototype) 'C' assumes that all functions return int and take no parameters [1].

Therefore you can call library functions without specifying a prototype provided that they take no parameters and the return value is either not used, or is assignment-compatible with 'int'.

You must provide a prototype if you want your library function to take any parameters, or you'll get error C267, "requires ANSI-style prototype"

But it's always good practice to provide function prototypes, as this gives the compiler the chance to warn you of type mismatches.

[1] kernighan & Ritchie
"The C Programming Language, 2/ed"
Prentice-Hall, 1988.

Probably you are right - I never use functions that take or return any parameter - it's too slow.
Michael.

Too slow? What are you talking about? Show me the assembler to back that statement up. It is extremely bad style and unsafe to use globals to pass information between functions.

Besides if your functions are void func(void) and you don't prototype them you should get a warning since C expects you return int.

- Mark

Quite right!

It's also unsafe & bad style to have a build in which warnings are normal.

One day there will be one extra warning, and that one will indicate a real problem in your code.
If your build is normally littered with warnings, that'd be easy to miss and the problem could get through into products and jump up and bite in some obscure fashion at some inopportune moment.
But if your build is normally "clean," a new warninng would stand out like a sore thumb and you could easily catch it before it bites.

Been there...

I am very pleased to know that the final judgement is delivered - which style is good and which is bad. Far from trying to alter it I would like to remark that I personally like the style that is more profitable - and do not impose my opinion.
Michael.

Any statement made by me is my opinion based upon 13 years of experience. I by no means meant it as some "final judgement" as you say. Sorry if you took it that way.

Regards.

- Mark