PHP OOPLesson 49Free preview

PHP Constants

This lesson is part of PHP · All levels

Summary

A constant is a fixed value that is defined once and cannot be changed during the run of a script. PHP provides the define() function to create global constants and the const keyword for both class and file contexts. A constant is suitable for configurations such as a basic URL, application mode, or fixed numeric values.

Key points

The constant is not initiated by the $ sign and its value cannot be changed once it is created.
Define() is a function, whereas const is a language constructor that should be at file/class level.
Got a third parameter to make names less sensitive to capital letters.
The constant value is taken by writing its name directly or via the function constant().

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