Multiple line comment inside multiple line comment in PHP

Question

<?php
/*
    /* this is a comment */
*/
?>

PHP returns "syntax error"... Is this just a completely wrong way to use multiple line comment?

Sometimes I need to comment out a big block of code for testing, and this block contains hundreds of lines and there are many multiple line comments inside.

What's the best way to comment out this big block? Besides removing it temporarily from the file?

Why would you want to do that?

Peter Mortensen
– Peter Mortensen

2022-01-31 14:10:04 +00:00
Commented Jan 31, 2022 at 14:10 — Peter Mortensen
– Peter Mortensen, Commented Jan 31, 2022 at 14:10

karim79 · Accepted Answer · 2011-08-08 03:55:07Z

14

From the PHP manual:

'C' style comments end at the first */ encountered. Make sure you don't nest 'C' style comments. It is easy to make this mistake if you are trying to comment out a large block of code.
<?php
 /*
    echo 'This is a test'; /* This comment will cause a problem */
 */
?>

:(

answered Aug 8, 2011 at 3:55

karim79

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5 Comments

dudeMatt Over a year ago

so are you saying that the only thing I could do is to either use bunch of // inside a multiple line comment or remove the block temporarily from the file?

karim79 Over a year ago

@dudeMatt - Yes, unfortunately - or use an IDE which does 'mass replacement' well. Or create your own script.

karim79 Over a year ago

It's unreliable because it is feasible to have /* or */ within regular expressions, anyway.

bertzzie Over a year ago

To add to the answer, your FIRST comment block ends when the second comment block ends. So the first comment block become /* echo ... */, and then the last */ is readen as code.

maximumcallstack Over a year ago

From my understanding comments should be used to detail syntax but only to describe what the block, or statement is doing. Ideally there shouldn't be any regex inside comments.

McKean · Accepted Answer · 2015-01-06 16:39:07Z

9

There's no nice way to do this so what I usually do is to just use the following workaround:

<?php if(false): ?>

Whatever needs to be commented out.

<?php endif; ?>

answered Jan 6, 2015 at 16:39

McKean

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2 Comments

Dano Over a year ago

I use a similar approach with function ignore(){ ... }

McKean Over a year ago

also works... ultimately I started letting my ide do the work... in vim you can easily set your motion to gc and let it add slashes all over the place...

kenorb · Accepted Answer · 2014-04-18 22:56:12Z

2

By design PHP syntax won't allow to do that.

So I think the easiest way to achieve that would be to remove all / characters followed by *.

In example, the following code:

/*

  /*
   * Comment 1
   */

  /*
   * Comment 2
   */

*/

would become:

/*

  /*
   * Comment 1
   *

  /*
   * Comment 2
   *

*/

answered Apr 18, 2014 at 22:56

kenorb

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Comments

Joe Enos · Accepted Answer · 2011-08-08 04:15:45Z

1

I'd say it depends on your IDE/editor. Some IDE's have a "comment" feature, which will do single-line comments (//) on all lines of a selected area, so you would select the whole range and click that button.

If your IDE doesn't have that feature, then I think you're out of luck.

For example, suppose this is your original code

$a = 1; /* sets a = 1 */
$b = 2;
/*
    blah blah
*/

If you highlight that whole thing in some IDEs and click the comment button, you'll end up with:

// $a = 1; /* sets a = 1 */
// $b = 2;
// /*
//     blah blah
// */

The // comments win, which mean you just did what you're trying to accomplish.

edited Aug 8, 2011 at 4:15

answered Aug 8, 2011 at 3:56

Joe Enos

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7 Comments

dudeMatt Over a year ago

IDE? Editor? what kind of editor would tell PHP to comment code MY way? NO! it's a PHP related problem...nothing to do with editors...

Joe Enos Over a year ago

Dude, relax. All I'm saying is that if your IDE lets you do a one-click comment using single-line comments, then you can comment multiple lines with one click, and it won't matter if there are multi-line comments in that batch. See my edit.

karim79 Over a year ago

Ahhh, brings back memories of eclipse... 'Ctrl->/' and all is commented

karim79 Over a year ago

@dudeMatt - if it makes you feel any better, the same problem exists in JavaScript, "never not use // in JavaScript because teh lolzboat cud sink" (Oscar Wilde, 1748).

dudeMatt Over a year ago

@Joe, alright, my bad. yes, I'm using EditPlus and it does have that feature, but after all it looks bad to me with so many //.

|

Avatar · Accepted Answer · 2018-11-14 06:03:22Z

1

Quick solution for the nested comment:

Turn the closing */ into a * /

In other words: Just set one whitespace.

answered Nov 14, 2018 at 6:03

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Comments

Peter Mortensen · Accepted Answer · 2022-02-01 18:59:36Z

0

For a smart move, just add and save your whole desired comment code section in "yourCodeBlock.php" and then:

<?php
/*
include("yourCodeBlock.php");
*/
?>

or a simple single line comment

<?php
//include("yourCodeBlock.php");
?>

edited Feb 1, 2022 at 18:59

Peter Mortensen

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answered Oct 30, 2017 at 18:25

Hassan Saeed

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