PHP Constants

Constants are similar to variables (as they are used to store some data) but they have a fixed value: you cannot modify a constant after you have defined it.

In PHP constants can be defined by using the keyword define. It's considered good practice to use uppercase names for constants.


<?php #constants.php
//defining a constant

define("USERNAME", "John");

//using the constant
echo "<p>Hello, <strong>" . USERNAME . "</strong>.</p>";

Hello, John.


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