PHP Constant

PHP constant is an identifier(name) for a simple value. The value does not change during the script. It starts with a letter or underscore not $ sign. The define()function is used to create a constant. Syntax:

define(name, value, case-insensitive);

Example:

<!DOCTYPE html>
<html>
<body>
<?php
// case-sensitive constant name
define("GREETING", "Welcome to PHP Tutorial");
echo GREETING;
?>
</body>
</html>

Output Welcome to PHP Tutorial Constants are Global PHP constant is automatically global. It can be used for entire script.Let’s take an example. Example

<?php
define("GREETING", "Welcome to PHP Tutorial");
functionmyTest() {
echo GREETING;
}
myTest();
?>