Space between line-comment character(s) and start of actual comment

Question

I realize that this rule might differ from one company's coding standards to another, but in general, which is preferred?

1. With a space after the line-comment:

   int foo = Bar(quux + 1); // compensate for quux being off by 1  foo = Bar(quux + 1) # compensate for quux being off by 1 

2. No space after the line comment:

   int foo = Bar(quux + 1); //compensate for quux being off by 1  foo = Bar(quux + 1) #compensate for quux being off by 1 

I haven't been able to find anything online regarding this aspect of coding style. My guess is that including a space is the preferred style for all languages, but I'd like some "hard evidence" to confirm or deny this.

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It sounds so far like everyone has anecdotal evidence that using a space is preferred. Can anyone point me in the direction of some official or otherwise published coding standards that directly address the issue of comment formatting and whether a space should be used?

Answer 1

I've developed software in many languages for about 10 years on projects large and small. I have yet to see anyone intentionally not use a space. In the scheme of things it doesn't really matter that much (after all, we all know those are comments and can read them), but I do think the no-space version looks similar to commented-out code and requires an extra millisecond of brain power to confirm it is a comment :-)

Answer 2

Python's official style guide, PEP 8, is very clear about this issue:

Each line of a block comment starts with a # and a single space (unless it is indented text inside the comment).

and:

Inline comments should be separated by at least two spaces from the statement. They should start with a # and a single space.

This confirms everybody's anecdotal evidence, but I think this is the first answer to quote "some official or otherwise published coding standards" as requested;-).