note in php code example

Example 1: 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 2: comment in php

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 */