How to use php const constant modifier_PHP tutorial
If we want to define constants in PHP, there are many ways to do it, but if we want to define constants in a class, we will most likely use the const constant modifier to define them. Let me introduce the operation method to you.
Defining constants in PHP is done through the define() function, but defining constants in a class cannot use define(), but requires the const modifier. After constants in a class are defined using const, their access methods are similar to static members. They are accessed through the class name or using self in the member method. However, after PHP 5.3.0, they can also be accessed using objects. A constant defined by const cannot be reassigned, and an error will occur if you try to change its value in the program.
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const CONSTANT = 'CONSTANT value' ; //Use const to declare a constant and assign the initial value directly
" ;//Use self to access constants, be careful not to add "$" before the constants } echo MyClass:: CONSTANT . " " ; //Use the class name to access constants outside the class, and do not add "$" $class = new MyClass(); $class->showConstant(); echo $class ::CONSTANT; // After PHP 5.3.0 ?> Attention to details: There is no need to use the "$" symbol before a constant name defined using const, and constant names are usually in uppercase. Attempting to assign a value to a constant defined by const will result in an error.
The program running result will be wrong.
There is no dollar sign ($) in front of the constant;
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