PHP uses recursive functions to create multi-level directories-PHP Tutorial-php.cn

PHP uses recursive functions to create multi-level directories

墨辰丷

Release： 2023-03-30 06:32:02

Original

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This article mainly introduces the use of recursive functions in PHP to create multi-level directories. Interested friends can refer to it. I hope it will be helpful to everyone.

The details are as follows:

function Directory($dir){
　　　　if(is_dir($dir) || @mkdir($dir,0777)){ //查看目录是否已经存在或尝试创建，加一个@抑制符号是因为第一次创建失败，会报一个“父目录不存在”的警告。

　　　　　　　　echo $dir."创建成功<br>";  //输出创建成功的目录

　　　　}else{

　　　　　　　　$dirArr=explode(&#39;/&#39;,$dir); //当子目录没创建成功时，试图创建父目录，用explode()函数以&#39;/&#39;分隔符切割成一个数组
　　　　　　　　array_pop($dirArr); //将数组中的最后一项（即子目录）弹出来，
　　　　　　　　$newDir=implode(&#39;/&#39;,$dirArr); //重新组合成一个文件夹字符串
　　　　　　　　Directory($newDir); //试图创建父目录
　　　　　　　　if(@mkdir($dir,0777)){
　　　　　　　　　　　　echo $dir."创建成功<br>";

　　　　　　　　} //再次试图创建子目录,成功输出目录名
　　　　}
}

Directory("A/B/C/D/E/F");

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The output result is as shown in the figure:

But it can be seen that it is too troublesome to write. Looking at the file functions in the manual, I saw a dirname() function, whose prototype is as follows:

##string dirname ( string $path )

Given a string containing the full path to a file, this function returns the directory name after removing the file name.

In Windows, both slash (/) and backslash (\) can be used as directory separators. In other circumstances it is a slash (/).

Can be slightly optimized:

function Directory($dir){

　　　　if(is_dir($dir) || @mkdir($dir,0777)){ 

　　　　　　　　echo $dir."创建成功<br>";  

　　　　}else{

　　　　　　　　Directory(dirname($dir));

　　　　　　　　if(@mkdir($dir,0777)){

　　　　　　　　　　　　echo $dir."创建成功<br>";

　　　　　　　　}

　　　　}

}

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The effect is the same. After that, I searched for answers on the Internet and found an
unusually insightful :

function Directory( $dir ){  

   return  is_dir ( $dir ) or Directory(dirname( $dir )) and  mkdir ( $dir , 0777);

}

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Now let’s explain the entire function:

First introduce the priority order of logical operators in PHP

: && > || > and > or, that is, symbolic type > letter type, AND type >OR type, so the function body can be seen as:

is_dir ( $dir ) or (Directory(dirname( $dir )) and mkdir ( $dir , 0777));

First determine whether the target directory exists. If it exists, depending on the short-circuit characteristics of or, the entire following will be short-circuited and execution will be skipped; if the target directory does not exist, the following function body will be executed:

Directory(dirname( $dir )) and mkdir ( $dir , 0777)

I thought about it

Do the recursion first Purpose: Execute recursion first to confirm that its parent directory (dirname($dir)) has been created, so that the subsequent mkdir() function will not issue a warning when it cannot find the parent directory when creating a subdirectory.

After entering the depth of the recursion, after confirming that the deepest root directory exists, create directories in sequence from the root directory downwards.

Finally, I suggest those who are looking for a job to go online and find some interview questions from large companies to do. After all, their exams are more comprehensive and in-depth. When learning knowledge, you should also brush up on the questions. In addition, you must also I have to do it a little bit, because it’s easy to have too much ambition but too little. I optimized the function at the beginning several times before it could be used normally.

This is an interview question about recursively creating a multi-level directory in PHP. In the future, the editor will find some interesting interview questions to share with you.

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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