The function to define constants in php is

The function used to define constants in PHP is define(), its usage is as follows: define(string $name, mixed $value, bool $case_insensitive = false); Parameters: name is the name of the constant, value is The value of the constant, case_insensitive sets whether the constant name is case-sensitive (default false) Return value: None

Function to define constants in PHP

In PHP, you can use the define() function to define constants.

Usage:

<code class="php">define(string $name, mixed $value, bool $case_insensitive = false);</code>

Parameters:

• $name: The name of the constant . Must be a valid identifier.
• $value: The value of the constant. Can be any data type, including number, string, boolean, or array.
• $case_insensitive (optional): If set to true, names of constants will be case-insensitive. The default is false, indicating case sensitivity.

Return value:

define() The function does not return any value.

Example:

Define a constant named GRAVITY with a value of 9.81:

<code class="php">define('GRAVITY', 9.81);</code>

Define a constant named # Constants for ##MY_ARRAY whose value is an array:

<code class="php">define('MY_ARRAY', ['foo', 'bar', 'baz']);</code>

Now, these constants can be used anywhere:

<code class="php">echo GRAVITY; // 输出 9.81
echo MY_ARRAY[0]; // 输出 foo</code>

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