关于include和include_once在使用上的意义-PHP Tutorial-php.cn

Home

Backend Development

PHP Tutorial

关于include和include_once在使用上的意义

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 23, 2016 pm 02:24 PM

一般导入一个文件，都是只需要导入一次即可，那么为什么还存在include？require同理。

回复讨论(解决方案)

在 php5 以前，include 和 require 是有区别
include 在运行期间执行，require 在预编译期间执行

php5 是两者都在预编译期间执行加载

include_once 和 require_once 用于防止重复加载
对于小系统，你是可以自行保证只加载一次。但对于大一点的系统，做到这一点就不是很容易的了

我不是问include和require的区别，这我知道。
我问的是，不是一直用include_once或require_once的就可以了吗？为什么还要用include和require？
写了一段时间代码都没发现在什么情况下需要导入一个文件多次。

include 直接加载文件
include_once 检查到没有加载时才加载

显然后者要多做一些事情

明白了，感谢！

我不是问include和require的区别，这我知道。
我问的是，不是一直用include_once或require_once的就可以了吗？为什么还要用include和require？
写了一段时间代码都没发现在什么情况下需要导入一个文件多次。
并不是说你的代码一次要加载一个文件多次，而是在引用多个文件里可能已经加载了，但是在该文件又加载了一次，这种情况用include...

Statement

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

11 Best PHP URL Shortener Scripts (Free and Premium)Mar 03, 2025 am 10:49 AM

Long URLs, often cluttered with keywords and tracking parameters, can deter visitors. A URL shortening script offers a solution, creating concise links ideal for social media and other platforms. These scripts are valuable for individual websites a

Working with Flash Session Data in LaravelMar 12, 2025 pm 05:08 PM

Laravel simplifies handling temporary session data using its intuitive flash methods. This is perfect for displaying brief messages, alerts, or notifications within your application. Data persists only for the subsequent request by default: $request-

Build a React App With a Laravel Back End: Part 2, ReactMar 04, 2025 am 09:33 AM

This is the second and final part of the series on building a React application with a Laravel back-end. In the first part of the series, we created a RESTful API using Laravel for a basic product-listing application. In this tutorial, we will be dev

Simplified HTTP Response Mocking in Laravel TestsMar 12, 2025 pm 05:09 PM

Laravel provides concise HTTP response simulation syntax, simplifying HTTP interaction testing. This approach significantly reduces code redundancy while making your test simulation more intuitive. The basic implementation provides a variety of response type shortcuts: use Illuminate\Support\Facades\Http; Http::fake([ 'google.com' => 'Hello World', 'github.com' => ['foo' => 'bar'], 'forge.laravel.com' =>

cURL in PHP: How to Use the PHP cURL Extension in REST APIsMar 14, 2025 am 11:42 AM

The PHP Client URL (cURL) extension is a powerful tool for developers, enabling seamless interaction with remote servers and REST APIs. By leveraging libcurl, a well-respected multi-protocol file transfer library, PHP cURL facilitates efficient execution of various network protocols, including HTTP, HTTPS, and FTP. This extension offers granular control over HTTP requests, supports multiple concurrent operations, and provides built-in security features.

12 Best PHP Chat Scripts on CodeCanyonMar 13, 2025 pm 12:08 PM

Do you want to provide real-time, instant solutions to your customers' most pressing problems? Live chat lets you have real-time conversations with customers and resolve their problems instantly. It allows you to provide faster service to your custom

Announcement of 2025 PHP Situation SurveyMar 03, 2025 pm 04:20 PM

The 2025 PHP Landscape Survey investigates current PHP development trends. It explores framework usage, deployment methods, and challenges, aiming to provide insights for developers and businesses. The survey anticipates growth in modern PHP versio

Notifications in LaravelMar 04, 2025 am 09:22 AM

In this article, we're going to explore the notification system in the Laravel web framework. The notification system in Laravel allows you to send notifications to users over different channels. Today, we'll discuss how you can send notifications ov

See all articles