Constants are quantities that cannot be changed. The define and const keywords are used in PHP to define constants. The following article will introduce to you how to define array constants in PHP. Let's take a look at the specific content.
Let’s take a brief look at define and const
define is a Universal constants used everywhere.
Because define has the characteristics of global scope, even if it is defined in a function, it also has the characteristics of being able to be referenced outside the function. If the function is executed again, a double definition error will occur, so it is usually defined outside the function.
const is used to define constants as members of class. This is a static member of the class, described as classname::constname.
Let’s take a look atThe basic method of defining a constant array
define('常量数组名1', ['值1', '键2' => '值2']); // 常量数组的定义 echo 常量数组名1['键2']; // 常量数组元素的参考 foreach (常量数组名1 as $value) { // 使用循环 echo $value; } class 类名 { const 常量数组名2 = ['值3', '键4' => '值4']; // 常量数组的定义 } echo 类名::常量数组名2['键4']; // 常量数组元素的参考 foreach (类名::常量数组名2 as $value) { // 使用循环 echo $value; }
Let’s take a look at a specific example
The code is as follows
<?php define('STATUS', [100=>'未请求',200=>'请求确认付款',300=>'确认收款']); class Prefecture { const NAMES = ['合肥','南京','上海','杭州']; public function show($id) { echo self::NAMES[$id], PHP_EOL; } } print_r(STATUS); echo STATUS[200], PHP_EOL; print_r(Prefecture::NAMES); echo Prefecture::NAMES[0], PHP_EOL; $prefecture = new Prefecture; $prefecture->show(2);
The execution results are as follows
This article ends here. For more exciting content, you can pay attention to the relevant columns of the php Chinese website for further study! ! !
The above is the detailed content of How to implement constant array in php? Introduction to how to define array constants in php. For more information, please follow other related articles on the PHP Chinese website!