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Constants

Variables offer a flexible way of storing data. You can change their values and the type of data they store at any time. However, if you want to work with a value that you want to remain unchanged throughout your script's execution, you can define and use a constant. You must use PHP's built-in define() function to create a constant, which subsequently cannot be changed. To use the define() function, you must place the name of the constant and the value you want to give it within parentheses, separated by a comma:

define("CONSTANT_NAME", 42);

The value you want to set can be a number, a string, or a Boolean. By convention, the name of the constant should be in capital letters. Constants are accessed with the constant name only; no ...