Can I use a hash sign (#) for commenting in PHP?

Question

I have never, ever, seen a PHP file using hashes (#) for commenting. But today I realized that I actually can! I\'m assuming there\'s a reason why everybody uses

Answer 1

One might think that the # form of commenting is primarily intended to make a shell script using the familiar "shebang" (#!) notation. In the following script, PHP should ignore the first line because it is also a comment. Example:

#!/usr/bin/php

If you store it in an executable file you can then run it from a terminal like this

./hello

The output is

Hello PHP

However, this reasoning is incorrect, as the following counterexample shows:

#!/usr/bin/php
#A

The first line (the shebang line) is specially ignored by the interpreter. The comment line before the PHP tag is echoed to standard output because it is not inside a PHP tag. The comment after the opening PHP tag is interpreted as PHP code but it is ignored because it is a comment.

The output of the revised version is

#A
Hello PHP