What is the usage of php define function

php define function usage: [define()] function defines a constant, the syntax is [define(name,value,case_insensitive)], defines a case-sensitive constant, the code is [define("GREETING ","Hello 】.

The operating environment of this tutorial: windows7 system, PHP5.6 version, DELL G3 computer. This method is suitable for all brands of computers.

Usage of php define function:

define() The function defines a constant.

Constant is similar to a variable, except that:

• After setting, the value of the constant cannot be changed

• The constant name does not require a dollar sign ($) at the beginning

• Scope does not affect access to constants

• Constant values ​​can only be strings or numbers

Syntax

define(name,value,case_insensitive)

Example 1

Define a case-insensitive constant:

<?php
define("GREETING","Hello world!");
echo constant("GREETING");
?>

Output:

Hello world!

Example 2

Define a case-insensitive constant :

<?php
define("GREETING","Hello world!",TRUE);
echo constant("greeting");
?>

Output:

Hello world!

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