La syntaxe de base
it's perhaps not obvious to some, but the following code will cause a parse error! the ?> in //?> is not treated as commented text, this is a result of having to handle code on one line such as <?php echo 'something'; //comment ?>
<?php
if(1==1)
{
//?>
}
?>
i discovered this "anomally" when i commented out a line of code containing a regex which itself contained ?>, with the // style comment.
e.g. //preg_match('/^(?>c|b)at$/', 'cat', $matches);
will cause an error while commented! using /**/ style comments provides a solution. i don't know about # style comments, i don't ever personally use them.
Commentaires
PHP supporte les commentaires de type C, C++ et Shell Unix (aussi appelé style Perl). Par exemple :
Exemple #1 Exemple de commentaire
<?php
echo 'Ceci est un test'; // Ceci est un commentaire sur une seule ligne, style c++
/* Ceci est un commentaire sur
plusieurs lignes */
echo 'Ceci est un autre test';
echo 'Et un test final'; # Ceci est un commentaire style shell sur une seule ligne
?>
Les commentaires sur une seule ligne comment jusqu'à la fin de la ligne ou le bloc courant de code PHP, le premier des deux. Ceci signifie que le code HTML après // ... ?> ou après # ... ?> SERA affiché : ?> terminera le mode PHP et retournera en mode HTML, et // ou # n'influencera pas cela. Si la directive de configuration asp_tags est activée, ce comportement sera identique avec // %> et # %>. Cependant, la balise </script> ne terminera pas le mode PHP dans un commentaire d'une seule ligne.
Exemple #2 Les commentaires vont jusqu'à la fin de la ligne
<h1>Ceci est un exemple <?php # echo 'simple';?>.</h1>
<p>La ligne ci-dessus affichera 'Ceci est un exemple'.</p>
Les commentaires style 'C' commentent jusqu'à ce que le premier */ soit rencontré. Vous devriez faire attention aux commentaires style 'C' nichés dans de gros blocs lorsque vous les commentez.
Exemple #3 Les commentaires de type C
<?php
/*
echo 'Ceci est un test'; /* Ce commentaire posera un problème */
*/
?>
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User Contributed NotesCommentaires
theblazingangel at aol dot com
29-Aug-2007 01:55
29-Aug-2007 01:55
fun at nybbles dot com
14-Jul-2006 08:28
14-Jul-2006 08:28
a trick I have used in all languages to temporarily block out large sections (usually for test/debug/new-feature purposes), is to set (or define) a var at the top, and use that to conditionally comment the blocks; an added benefit over if(0) (samuli's comment from nov'05) is that u can have several versions or tests running at once, and u dont require cleanup later if u want to keep the blocks in: just reset the var.
personally, I use this more to conditionally include code for new feature testing, than to block it out,,,, but hey, to each their own :)
this is also the only safe way I know of to easily nest comments in any language, and great for multi-file use, if the conditional variables are placed in an include :)
for example, placed at top of file:
<?php $ver3 = TRUE;
$debug2 = FALSE;
?>
and then deeper inside the file:
<?php if ($ver3) {
print("This code is included since we are testing version 3");
}
?>
<?php if ($debug2) {
print("This code is 'commented' out");
}
?>
mst_NO_SPAM_TO_ME at mstsoft dot com
05-Jun-2006 03:38
05-Jun-2006 03:38
This "comment ends on line break or end of PHP Block" thing can be confusing. I discovered this by accident when working with XML Output from PHP...
<?PHP
header("Content-type: text/xml");
/*
echo "<?xml version=\"1.0\"?>";
echo "<page>multi-line comments work as expected.</page>";
*/
//echo "<?xml version=\"1.0\"?>";
//echo "<page>single-line comments end php mode and output your code.</page>";
?>
I would expect the comment to work, but there is no parsing in comments so the String suddenly becomes a PHP end-block tag, which is correct reading this documentation.
cheers,
martin
PS: You even see the behavior in the Syntax highlighting :-)
J Lee
26-May-2006 09:39
26-May-2006 09:39
MSpreij (8-May-2005) says /* .. */ overrides //
Anonymous (26-Jan-2006) says // overrides /* .. */
Actually, both are correct. Once a comment is opened, *everything* is ignored until the end of the comment (or the end of the php block) is reached.
Thus, if a comment is opened with:
// then /* and */ are "overridden" until after end-of-line
/* then // is "overridden" until after */
21-Jan-2006 11:46
M Spreij wrote, 08-May-2005 08:15...
A nice way to toggle the commenting of blocks of code can be done by mixing the two comment styles:
...
This works because a /* .. */ overrides //.
The final sentence should be the other way round, i.e.
This works because a // overrides /* .. */.
(If it didn't the /* .. */ would comment out the code regardless of whether an additional '/' is prefixed to the first line).
samuli dot karevaara at lamk dot fi
11-Nov-2005 06:30
11-Nov-2005 06:30
If you want to comment out large sections of code (temporarily, usually and hopefully), consider using
<?php
if (0) {
print("This code is 'commented' out");
}
?>
instead of /* comment block */. Otherwise, as noted here, you will have parse errors if the block that you commented out contains */ somewhere, like in regexp or in another comment.
hcderaad at wanadoo dot nl
29-Jun-2005 11:51
29-Jun-2005 11:51
Comments in PHP can be used for several purposes, a very interesting one being that you can generate API documentation directly from them by using PHPDocumentor (http://www.phpdoc.org/).
Therefor one has to use a JavaDoc-like comment syntax (conforms to the DocBook DTD), example:
<?php
/**
* The second * here opens the DocBook commentblock, which could later on<br>
* in your development cycle save you a lot of time by preventing you having to rewrite<br>
* major documentation parts to generate some usable form of documentation.
*/
?>
Some basic html-like formatting is supported with this (ie <br> tags) to create something of a layout.
M Spreij
08-May-2005 10:15
08-May-2005 10:15
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 02:41
15-Dec-2004 02:41
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.*/');
*/
?>