proper commenting in C

joesbox · 02-13-2005, 08:10 AM

i am just starting to learn C and had a simple question for anyone that would like to answer. i picked up a book called Visual Quickstart Guide: C Programming by Larry Ullman and Marc Liyanage. in the book it makes reference to commenting using the /* comment */ style but i have seen one comment using // with no end comment or anything like */. example from the book

Code:

/* hello3.c - Script 1.4
 * Created by Larry Ullman 5/6/2004
 * This script says "Hello, world!"
*/

#include <stdio.h>

int main (void) {

printf("Hello, world!");
getchar(); // wait for the user before continuing. 

return 0;

}

now the commenting is understandable but i was wondering which is best to use? i have seen all types of commenting styles from # to ! to /* to //.
i hope that this isn't a stupid question and that it really doesn't relate to actual coding but i would like to remain standard so that my comments are readable to the rest of the world since i plan on making all my future code open source.
thanks in advance
Joe
*any mistakes in the code are due to typo of me.

Starch · 02-13-2005, 08:21 AM

The standart for C is using /* */, but compilers now accept "//" for C code. Use which ever is more convenient For Example if you will explain about a function with about 3 lines of explanation than /* */ is better and all C/C++ compilers support it.

If you are explaining code line by line than using "/* */" would look more messy than "//"

If you plan on releasing your code make sure you comment what each relevant function does. The more you will comment the easier it will make it for others to upgrade or add add-ons to your project. But remember don't comment too much or too little.

Have fun!

Miaire · 02-13-2005, 08:22 AM

Most I have seen are /* */ and personally, I find that they look neater even if you're just commenting in/on one line.

joesbox · 02-13-2005, 09:09 AM

thanks guys. i thought that either worked but i just wanted to make sure if there was a standard to use or not. for simplicity sake i will probably just use the /* */ even if it is a little messy.

deiussum · 02-13-2005, 10:11 AM

Using // is C++ style commenting, but as stated, most C compilers also support it. Using // is nice for simple comments for individual lines not only for convenience, but because it is then easier to comment out whole blocks of code. For instance, consider something like the following:

Code:

/* Comment out this whole function for whatever reason
int someFunction()
{
    blah blah; /* something something */   
}
*/

The above won't work to comment the entire function because the commenting inside the function will close out the comment early. If you commented it inside the function with // instead, you wouldn't have that problem.

joesbox · 02-13-2005, 11:53 AM

that is a very important point that will help in debugging later. thanks a lot deiussum. i probably would have done this later and not knows the reason for the error. i will definitely keep this in mind.

lyle_s · 02-13-2005, 11:11 PM

Quote:

Originally posted by Starch
The standard for C is using /* */, but compilers now accept "//"

The newest C language standard, C99, includes "//" style comments.

Lyle