PHP Constants

title: Constants


Constants are a type of variable in PHP. The define() function to set a constant takes three arguments – the key name, the key’s value, and a Boolean (true or false) which determines whether the key’s name is case-insensitive (false by default). A constant’s value cannot be altered once it is set. It is used for values which rarely change (for example a database password OR api key).


It is important to know that unlike variables, constants ALWAYS have a global scope and can be accessed from any function in the script.


<?php define("Codevarsity", "Learn to code and help nonprofits", false); echo Codevarsity;


Learn to code and help nonprofits

Also, when you are creating classes, you can declare your own constants.

class Human { const TYPE_MALE = 'm'; const TYPE_FEMALE = 'f'; const TYPE_UNKNOWN = 'u'; // When user didn't select his gender ............. }

Note: If you want to use those constants inside the Human class, you can refer them as self::CONSTANT_NAME. If you want to use them outside the class, you need to refer them as Human::CONSTANT_NAME.

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