Php/docs/language.basic-syntax.comments

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Comments

PHP supports 'C', 'C++' and Unix shell-style (Perl style) comments. For example:

<?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?>

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 HTML code after // ... ?> or # ... ?> WILL be printed: ?> breaks out of PHP mode and returns to HTML mode, and // or # cannot influence that.

<h1>This is an <?php # echo 'simple';?> example</h1><p>The header above will say 'This is an  example'.</p>

'C' style comments end at the first */ encountered. Make sure you don't nest 'C' style comments. It is easy to make this mistake if you are trying to comment out a large block of code.

<?php /*    echo 'This is a test'; /* This comment will cause a problem */ */?>