Best way to give a variable a default value (simulate Perl ||, ||= )

The best way to give a variable a default value in PHP is to use the null coalesce operator ?? (available in PHP 7.0+). For older versions, the ternary operator ?: combined with isset() is commonly used. Both approaches simulate Perl's ||= operator, which assigns a default value if a variable is undefined or null.

Example of the best way to give a variable a default value in PHP with the ternary operator ?:

<?php

$var = isset($var) ? $var : 'default value';

echo $var;

This line of code checks if the variable $var is set, and if it is, it assigns its value to $var. If it is not set, it assigns the string 'default value' to $var. Note that isset() returns false if the variable is explicitly set to null, whereas the ?? operator handles null explicitly.

Another way is to use the null coalesce operator (??) in PHP 7 or later:

Example of using the null coalesce operator (??) in PHP 7 or later to give a variable a default value

<?php

$var = $var ?? 'default value';

echo $var;

This operator checks if the variable on the left is defined and not null. If it is, it uses that value; otherwise, it assigns the value on the right. It is the modern standard in PHP due to its concise syntax and explicit null handling.