要描述一个文件的位置,可以使用决对路径和相对路径。绝对路径是从根开始一级一级地进入各个子目录,最后指定该文件名或目录名。而相对目录是从当前目录进入某目录,最后指定该文件名或目录名。在系统的每个目录下都有两个特殊的目录“.”和“..”,分别指示当前目录和当前目录的父目录(上一级目录)。例如:
$unixPath = “/var/www/html/index.php”; –在UNIX系统中绝对路径,必须使用“/”作为路径分隔符
$winPath = “C:\\Appserv\\www\\index.php”; –Windows系统的绝对路径,默认使用“”作为路径分隔符
$winPath = “C:/Appserv/www/index.php”; –在Windows系统中也接受“/”作为路径分隔符,推荐使用
$fileName1=”file.txt”; –相对路径,当前目录下的file.txt文件
$fileName2=”javascript/common.js”; –相对路径,当前目录中javascript子目录下的common.js文件
$fileName3=”../images/logo.gif”; –相对路径,上一级目录中images子目录下的logo.gif文件
在上例中,分别列出了UNIX和Windows系统中绝对路径和相对路径的格式。其中在UNIX系统中必须使用正斜线“/”作为路径分隔符,而在Windows系统中默认使用反斜线“”作为路径分隔符,在程序中表示还要将“”转义,但也接受正斜线“/”作为分隔符的写法。为了程序可以有很好的移植性,建议都使用“/”作为文件的路径分隔符。另外,也可以使用PHP的内置常量DIRECTORY_SEPARATOR,其值为当前操作系统的默认文件路径分隔符。例如:
$fileName2 = “javascript”.DIRECTORY_SEPARATOR.”common.js”; –Unix为“/”,Windows为“”
将目录路径中各个属性分离开通常很有用,如末尾的扩展名、目录部分和基本名。可以通过PHP的系统函数basename()、dirname()和pathinfo()函数完成这些任务。
①函数basename()
函数basename()返回路径中的文件名部分。该函数的原型如下所示:
string basename(string path[,string suffix]) //返回路径中的文件名部分
该函数给出一个包含其指向一个文件的全路径的字符串,本函数返回基本的文件名。第二个参数可选参数,规定文件的扩展名。如果提供了则不会输出这个扩展名。该函数的使用如下面的代码所示:
//包含有指向一个文件的全部路径的字符串
$path = "/var/www/html/page.php";
//显示带有文件扩展名的文件名,输出page.php
echo basename($path);
//显示不带有文件扩展名的文件名,输出page
echo basename($path,".php");
?>
②函数dirname()
该函数恰好与basename()相反,只需要一个参数,给出一个包含有指向一个文件的全部路径的字符串,本函数返回去掉文件名后的目录名。该函数的使用如以下代码所示:
$path = "/var/www/html/page.php";
echo dirname($path); //返回目录名/var/www/html
echo dirname('c:/'); //返回目录名c:/
?>
③函数pathinfo()
函数pathinfo()返回一个关联数组,其中包括指定路径中的目录名、基本名和扩展名三个部分。分别通过数组键dirname、basename和extension来引用。该函数的使用如下代码所示。
$path = "/var/www/html/page.php";
$path_parts = pathinfo($path); //返回包括指定路径中的目录名、基本名和扩展名关联数组
echo $path_parts["dirname"]; //输出目录名/var/www/html
echo $path_parts["basename"]; //输出基本名page.php
echo $path_parts["extension"]; //输出扩展名.php
?>

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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