Constants in PHP are just like variables but their value can`t be change once set. It means you have to define the value of constants first and then you cannot change it.
- A perfect constant name can be start with a letter or underscore.
- Constants in PHP will automatically be global in the whole program.
Constants Syntax in PHP
The syntax of a constant in PHP is a define( ) function with some parameters which are (name, value, case-insensitive). As the name defines that the parameter of name is used for the name of constant. A value parameter is used to define the value of the constant. An important factor in constants is that they should be case-insensitive.
<!DOCTYPE html>
<html>
<body>
<?php
// case-sensitive constant name
define("MESSAGE", "Welcome to our website");
echo MESSAGE;
echo "<br>";
// case-insensitive constant name
define("MESSAGE", "Welcome to our website", true);
echo message;
?>
</body>
</html>
Constants Array in PHP
You can also create a constants array in PHP. This examples exactly shows it.
<!DOCTYPE html>
<html>
<body>
<?php
define("students", [
"Hamza",
"Ali",
"Zara"
]);
echo students[0];
echo "<br>";
echo students[1];
?>
</body>
</html>