Understanding PHP Constants
This article explores the basic concepts of defining and using PHP constants with examples.
Our discussion will cover constant syntax, types, and access within PHP scripts.
As a result of this article, you should have a solid understanding of PHP constants.
PHP Constants
PHP Constants are values that cannot be changed during script execution.
Once a constant is defined, it remains constant throughout the script.
There are many uses for constants, such as defining values that are not likely to change over time, such as configuration settings, mathematical constants, and other values specific to the application.
In order to identify a constant, it must begin with a letter or underscore (there is no $ sign preceding the constant name).
Set up a PHP constant
Using define(), you can create a constant.
The define() function takes two arguments: the constant name and the value.
Syntax
define(name, value, case-insensitive)
Defining parameters:
- CONSTANT_NAME: Name of the constant. All caps, numbers, and underscores are allowed. It’s useful to give your constants descriptive names so that they’re easily recognizable.
- constant_value: Constant_value is what you want to assign. Strings, integers, and floats can all be used here.
In the following example, create a case-sensitive constant name:
Example:
Following is another example for better understanding the constant name. Let’s create a case-sensitive constant name:
Example:
PHP Constant Arrays
PHP Constant can also be defined as array.
It can be useful for defining a set of parameters that should not change during script execution.
For example, configuration settings, language strings, and other application-specific values can be specified in constant arrays.
In the following example, Creating a constant for an array:
Example:
The following example shows the constant array of PETS:
Example:
Global PHP Constants
All constants in the PHP script are automatically global and are available for use across the entire script.
It doesn’t matter where the constant is accessed after it is defined; it stays in scope throughout the script.
The following example shows how a constant is used inside a function, even when it is defined outside of the function:
Example:
Example Explanation:
In above example we have define a constant named “MESSAGE” with the value “This const is from PHP“, and then define a function named “globalConstant” that echoes the constant “MESSAGE”.
Finally, the function is called, which would result in the output of the constant value “This const is from PHP“.
The constant “MESSAGE” is defined using the “define” statement, which is used to create a PHP constant.
Constants are named values that cannot be changed during the execution of a program.
Here is another example for better understanding that constants are global:
Example:
In conclusion, PHP Constants are a valuable feature that enables developers to define values that cannot be changed during the execution of the script. With the define() function, it is easy to create constants, and once they are defined, they are global throughout the entire script.
Constants can be useful for defining values such as configuration settings, mathematical constants, and other values specific to the application.
Additionally, constants can be defined as arrays, making it easy to specify a set of parameters that should not change during script execution. With the knowledge provided in this article, you should be able to create and use constants in your PHP applications effectively, leading to better code readability, maintainability, and security.
