PHP Comment
PHP comment is a very important part of the code. Comments make the code easier to read and maintain. PHP supports two style of comments:
- Single line comments
- Multiline comments
Single line comment is used for a quick note of a line of code and start with //. Let's take a look at an example using single line comment:
<?php
$payout = $x * $y; // payout calculation
?>
In the above example, single line comment starts with // and comment text.
Multiline comment is used to describe something in a greater depth such as complicated algorithm, business logic. Multiline comment starts with /* and end with */. Here is an example of using multiline comment.
<?php
function get_age($birth_date)
{
/*
- find the difference between current year and year of birth
- check if date_of_birth has not occurred this year yet, minus the age by 1
*/
list($year_of_birth,$month_of_birth,$date_of_birth) = explode("-", $birth_date);
$age = date("Y") - $year_of_birth;
$month_diff = date("m") - $month_of_birth;
$day_diff = date("d") - $date_of_birth;
if ($day_diff < 0 || $month_diff < 0)
$age--;
return $age;
}
?>
In the above example, the multiline comment is used to explain the logic of calculating age based on a given date of birth.
Be noted that PHP comment resides in PHP code file but PHP Interpreter does not output the PHP comments.
Tips on writing comment effectively
- Comment should be used to tell how a piece of code does instead of how it works.
- Comment is also written to helps other developers who maintains the code later easier to understand the code.