// comment
or
/* comment */

//comment is for a actual comments

/*comment*/ should only be used commenting out code

These are some unwritten rules

If it's a whole line comment, //
If it's a multi-line comment or commenting out something in the middle of the line, /* */

P.S. I kind of hate how VSCode handles those; I need an extra extension just to automatically insert the proper one, and selecting a whole comment block requires an absurd amount of steps. WebStorm was perfect in that.

--

# this is a comment
// this is another comment
; this is also a comment
/* this is another one */
/** ooh a bigger one **/
"" here's a good one
' fuck this is one too

Nope, I think that's all of them I've used this month so far.

@C0D4 Yeah, kind of silly that it was implied that only C-like syntaxes exist.

Depends, if it's a doclet, legal text or commented block of code then the multi-line one (although for doclets it would be /** */).
For the rest //.

"// Comment" is C++ style, not C
C only really have "/* Comment */"

I find "/* */" generally cleaner and use "//" mostly to comment out lines or shit while coding