What is a correct way to add a comment in PHP? code example

Example 1: php comment

// This is a single-line comment

# This is also a single-line comment

/*
This is a multiple-lines comment block
that spans over multiple
lines
*/

Example 2: php comment

<?php
// This is a single-line comment

# This is also a single-line comment
  
/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
  
// You can also use comments to leave out parts of a code line
$x = 5 /* + 15 */ + 5;
echo $x;
?>

Example 3: comment in php

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.
?>

Example 4: comment in php

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.*/');

*/

?>

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)-->*/