Comments

PHP supports 'C', 'C++' and Unix shell-style (Perl style) comments. For example:


<?php

    echo 'This is a test'; // This is a one-line c++ style comment

    /* This is a multi line comment

       yet another line of comment */

    echo 'This is yet another test';

    echo 'One Final Test'; # This is a shell-style comment

?>

The "one-line" comment styles only comment to the end of the line or the current block of PHP code, whichever comes first. This means that HTML code after // ?> WILL be printed: ?> skips out of the PHP mode and returns to HTML mode, and // cannot influence that. If asp_tags configuration directive is enabled, it behaves the same with // %>. However, </script> tag doesn't escape PHP mode in one-line comment.


<h1>This is an <?php # echo 'simple';?> example.</h1>

<p>The header above will say 'This is an example'.</p>

'C' style comments end by the first encountered */. You should be careful not to nest 'C' style comments, which can happen when commenting out large blocks.


<?php

 /* 

    echo 'This is a test'; /* This comment will cause a problem */

 */

?>

User Contributed Notes
Comments

M Spreij
08-May-2005 03:15


A nice way to toggle the commenting of blocks of code can be done by mixing the two comment styles:

<?php

//*

if ($foo) {

  echo $bar;

}

// */

sort($morecode);

?>



Now by taking out one / on the first line..



<?php

/*

if ($foo) {

  echo $bar;

}

// */

sort($morecode);

?>

..the block is suddenly commented out.

This works because a /* .. */ overrides //. You can even "flip" two blocks, like this:

<?php

//*

if ($foo) {

  echo $bar;

}

/*/

if ($bar) {

  echo $foo;

}

// */

?>

vs

<?php

/*

if ($foo) {

  echo $bar;

}

/*/

if ($bar) {

  echo $foo;

}

// */

?>

Steve
15-Dec-2004 07:41


Be careful when commenting out regular expressions.



E.g. the following causes a parser error.



I do prefer using # as regexp delimiter anyway so it won't hurt me ;-)



<?php 



/*



 $f->setPattern('/^\d.*/');



*/



?>

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