PHP program to check a constant is defined or not

Program/Source Code:

The source code to check a constant is defined or not is given below. The given program is compiled and executed successfully.

<?php
//PHP program to check a constant is defined or not.
define(PI,3.14);
    
if(defined("PI")==true)
	print("Constant is defined");
else
	print("Constant is not defined");
?>

Output:

Constant is defined

Explanation:

In the above program, we defined a constant PI initialized with 3.14. Then we checked constant PI is defined or not using the defined() method and then print the appropriate message on the webpage.