What are the potential pitfalls of using single quotes vs double quotes in defining constants in PHP?

Using single quotes to define constants in PHP can lead to issues when trying to include variables within the constant value, as single quotes do not parse variables. Double quotes allow for variable interpolation, making it easier to include variables within the constant value. To avoid potential pitfalls, it is recommended to use double quotes when defining constants that require variable interpolation.

define('CONSTANT_NAME', "This is a constant value with a $variable inside.");