Table of Contents 简介 if else elseif/else if switch
while do-while for foreach
break continue goto declare return require include require_once include_once
###简单说说:PHP文件包含语句有 include、include_once、require、require_once区别
<p class="sycode"> 1、include()格式1:include(path/filename);格式2:include 'filename';一、include()语句将在其被调用的位置处包含一个文件。包含一个文件与在该语句所在位置复制制定文件的数据具有相同内 </p> <p class="sycode"> 容的效果。使用include()时可以忽略括号。二、可以根据条件来执行include()语句。在条件语句中使用include()有个怪现象,它必须包围在语句块大括号中,或者用 </p> <p class="sycode"> 其他语句包围符括起来。<?php if(false){ include 'index.php'; }else{ include('index.php'); } ?> </p> <p class="sycode"> 2、include_once() 格式1:include_once(filename);格式2:include_once 'filename';include_once()函数的作用与include相同,不过它会首先验证是否已经包含了该文件。如果已经包含,则不再执行 </p> <p class="sycode"> include_once。否则,则必须包含该文件。除了这一点与include完全相同。3、require() 格式1:require(filename);格式2:require 'filename';require()在很大程度上与include相同,都是将一个模板文件包含到require调用坐在的位置。require和include之间有两点重要的区别: </p> <p class="sycode"> 首先,无论require的位置如何,制定文件都将包含到出现require的脚本中。例如,即使require放在计算结果为假的if语 </p> <p class="sycode"> 句中,依然会包含指定文件。 </p> <p class="sycode"> 第二个重要的区别是:require出错时,脚本将停止运行,而在使用include的情况下,脚本将继续执行。4、require_once() 格式1:require_once(filename);格式2:require_once 'filename';随着网站越来越大,可能会出现重复包含某些文件。这也许不是问题,但又是修改了所包含文件的变量后,却由于后面再次包 </p> <p class="sycode"> 含原来的文件而被覆盖,可能不希望出现这种情况。还可能出现另一个问题,即所包含文件中函数名的冲突。使用 </p> <p class="sycode"> require_once就可以解决这些问题。require_once函数确保文件只包含一次。在遇到require_once后,后面再试图包含相同的文件时将被忽略。include()在引入文件时候出错时,脚本会继续向下执行require() 在引入文件时候出错时,脚本不会继续向下执行 </p>
###流程控制的替代语法
PHP 提供了一些流程控制的替代语法,包括 if,while,for,foreach 和 switch。
替代语法的基本形式是把左花括号({)换成冒号(:),把右花括号(})分别换成endif;,endwhile;,endfor;,endforeach; 以及 endswitch;。
<p class="sycode"> <? php if ($a > $b) { echo " 123 " ;} elseif ($a == $b) { echo " 456 " ;} else { echo " 789 " ;} ?> </p>
<p class="sycode"> <? php if ( true ) : echo " 123 " ; elseif ( 2 == $b) : echo " 456 " ; echo " 789 " ; else : echo " 789 " ; echo " 789 " ; echo " 789 " ;endif ?> </p>
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What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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