PHP - Constants

PHP Constant is an identifier for a value like a variable but it has some unique characteristics such as,

• Once you create a constant then you cant change it
• Once you create a constant then you cant undefined it
• Value cannot be changed during the  script
• Constant Name starts with a Letter or underscore sign. There is no $ sign for constants.

How to set a PHP Constant
There is a key word calling "define" uses to define the constants in PHP.



Syntax:
define (<Constant Name>, <Value>, <true/false);
- 1st Parameter defines the name of the constant
- 2nd Parameter defines the value of the constant
- 3rd parameter is an optional to define whether the constant name is case sensitive or not, if case sensitive then uses true as the value.

Example:

Code:





Output: