What method is used to define constants in php

The syntax for defining constants in PHP: use the define() function, the syntax is define(string $name, mixed $value, bool $case_insensitive = false) The constant name must be a valid identifier (starting with a letter, which can Contains letters, numbers, underscores) constant value can be any valid data type Constant once defined cannot be changed Constant takes effect when defined, no need to import

PHP The syntax for defining constants in

In PHP, you can use the define() function to define constants. The syntax is:

<code>define(string $name, mixed $value, bool $case_insensitive = false) : bool</code>

Parameter description:

• $name: The name of the constant
• $value: The value of the constant
• $case_insensitive: Whether it is case-insensitive (optional, default is false, case-sensitive)

Usage example:

<code class="php">// 定义一个常量，名称为 PI，值为 3.14
define('PI', 3.14);

// 使用常量
echo PI; // 输出：3.14</code>

Note:

• The name of the constant must be a valid identifier, that is, letters, numbers, and underscores consists of and cannot begin with a number.
• The value of a constant can be any valid data type, including strings, numbers, Boolean values, etc.
• Once defined, constants cannot be changed.
• Constants take effect when they are defined and do not need to be imported using statements such as use or global.

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