<h1>This is an <?php # echo 'simple';?> example</h1>
<p>The header above will say 'This is an example'.</p>
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
/*
$f->setPattern('/^\d.*/');
*/
?>
A nice way to toggle the commenting of blocks of code can be done by mixing the two comment styles:
<?php
//*
if ($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;
}
// */
?>
<?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 one-line shell-style comment
?>
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 */
Notes can come in all sorts of shapes and sizes. They vary, and their uses are completely up to the person writing the code. However, I try to keep things consistent in my code that way it's easy for the next person to read. So something like this might help...
<?php
//======================================================================
// CATEGORY LARGE FONT
//======================================================================
//-----------------------------------------------------
// Sub-Category Smaller Font
//-----------------------------------------------------
/* Title Here Notice the First Letters are Capitalized */
# Option 1
# Option 2
# Option 3
/*
* This is a detailed explanation
* of something that should require
* several paragraphs of information.
*/
// This is a single line quote.
?>
Comments do NOT take up processing power.
So, for all the people who argue that comments are undesired because they take up processing power now have no reason to comment ;)
<?php
// Control
echo microtime(), "<br />"; // 0.25163600 1292450508
echo microtime(), "<br />"; // 0.25186000 1292450508
// Test
echo microtime(), "<br />"; // 0.25189700 1292450508
# TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST TEST
# .. Above comment repeated 18809 times ..
echo microtime(), "<br />"; // 0.25192100 1292450508
?>
They take up about the same amount of time (about meaning on a repeated testing, sometimes the difference between the control and the test was negative and sometimes positive).
<?php
// Author : https://www.codedweb.org/
// This is a single-line comment
# This is also a single-line comment in unix and linux
/*
This is a Multi-lines comment block
by this way you can add muliple lines on it.
lines
*/
// You can also use comments to leave out parts of a code line
$var = 2 /* + 12 */ + 2;
echo $var;
?>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.
<?php
/*
echo 'This is a test'; /* This comment will cause a problem */
*/
?>