Article Topic Learning Download Q&A Programming Dictionary Game Recent Updates

简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)

Home > Backend Development > PHP Tutorial > body text

Analysis of the difference between const and define in php

WBOY

Release： 2016-07-25 08:58:30

Original

933 people have browsed it

if (...) {
const FOO = 'BAR'; // invalid
}
but
if (...) {
define('FOO', 'BAR'); // valid
}

Copy code

4. const uses an ordinary constant name, and define can use an expression as the name. For example:

const FOO = 'BAR';
for ($i = 0; $i < 32; ++$i) {
define('BIT_' . $i, 1 << $i );
}

Copy code

5. const can only accept static scalars, while define can use any expression. For example:

const BIT_5 = 1 << 5; // invalid
but
define('BIT_5', 1 << 5); // valid

Copy code

6, const Always case-sensitive, however define() can define case-insensitive constants via the third argument. For example:

define('FOO', 'BAR', true);
echo FOO; // BAR
echo foo; // BAR

Copy code

From the above example, we get, const is simple and easy to read. It is a language structure in itself, while define is a method. Defining with const is much faster than define at compile time. As for which one to use, it depends on your own needs.

Related labels：

php中const与define的区别分析

source：php.cn

Previous article：Example code for implementing mass mailing using phpmailer class Next article：There are too many session files in php, the inode is used up, and the solution to the problem that apache cannot run

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn