how to comment php code code example

Example 1: comment in php

<?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;
?>

Example 2: php proper function comments

/**
 * This function compiles a message that tells you how great coffee is
 *
 * @param string  $compliment A nice word to describe coffee 
 * @param integer $score      A score out of 10
 */

Example 3: comment in php

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;
}
// */
?>

Example 4: comment in php

It is worth mentioning that, HTML comments have no meaning in PHP parser. So,

<!-- comment
<?php echo some_function(); ?>
-->

WILL execute some_function() and echo result inside HTML comment.

Example 5: comments in php

//For a single line comment use //:
//this is a comment too
//for multi-line comments use /* and */:
/* <--start of multi-line comment
this is a comment

this is a comment too (end of multi-line comment)-->*/

Example 6: comment in php

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.