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2.6.7 Comments

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While in PHP mode, you can mark certain parts of your code as a comment that should not be executed. PHP has three ways of doing this: //, /* */, and #. // and # mean, "ignore the rest of this line", whereas /* means "ignore everything until you see */". Some complications exist with /* and */, though, which make them less desirable to use.

<?php

      print "This is printed\n";

      // print "This is not printed\n";

      # print "This is not printed\n";

      print "This is printed\n";

      /* print "This is not printed\n";

      print "This is not printed\n"; */
 ?>

That chunk of code shows all three types of comments in action, but does not demonstrate the problem with the /* */ form of commenting. If you were to start a /* comment on line one, and end it on the line near the bottom where the other /* comment is started, you would find that the script would fail to work. The reason for this is that you cannot stack up, or "nest" /* */ comments, and attempting to do so will usually fail spectacularly.

It is generally best to stick to // for your commenting purposes, simply because it is easier to spot, easy to read, and easy to keep control of.

<< 2.6.6 Opening and closing code islands		2.6.8 Conditional statements >>
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A PHP User - 30 Aug 2008

WATCH OUT!! when using the one-line comment style.

As the PHP manual puts it: "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 the line

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

will parse to valid html, even though you wouldn't expect it if you have a C background. More of a bug than a feature IMHO.

A Fortran77 User ;o) - 30 Aug 2008

Commenting of your code can be used even far more effectively by combining it with a code documentation generator. People who have worked with C/C++ and specifically when programming with QT will most likely know of doxygen. (http://www.stack.nl/~dimitri/doxygen/)

Similar tools exists for PHP. The one I'm using currently is phpDocumentor (http://www.phpdoc.org/).

These tools use the /* */ convention, where a to be documented code comment should start with /**.

Here is an example of such a documentation comment:

/**
* Does action foo
*
* This function performs action foo using $arg1 to
* select status bar.
*
* @param string $arg1 Some parameter to use when performing foo.
*/
function doFoo($arg1)
{
// Perform some action
}

Cheers,
Luud Heck

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