php implements folder traversal

PHP is a very popular programming language that can be used to implement a variety of operations. Among them, traversing folders and obtaining file information therein is a frequently needed operation. In this article, I will explain how to implement folder traversal in PHP.

1. opendir() function

opendir() function is a function used by PHP to open a folder. When calling this function, you need to pass in the folder path as a parameter. After the folder is opened successfully, the contents of the folder can be read through the readdir() function.

Sample code:

$dir = './test';  //文件夹路径
$handle = opendir($dir);  //打开文件夹
while ($file = readdir($handle)) {  //循环读取所有文件
    if ($file != "." && $file != "..") {  //排除"."和".."两个特殊的文件夹
        echo $file."<br>";  //输出文件名
    }
}
closedir($handle);  //关闭文件夹

In the above sample code, I opened a folder named "test" and read all the file names in the folder in a loop, And ignore the two special folders "." and "..".

2. is_dir() function and recursive traversal

If we want to traverse all subdirectories and files in a directory, we can use the recursive method. During the traversal process, we also need to determine whether the current traversal is a folder or a file. We can use the is_dir() function to determine.

Sample code:

function scanDir($dir){
    if(!is_dir($dir)){
        echo '不是一个有效的文件夹路径';
        return;
    }
    $handle = opendir($dir);  //打开文件夹
    while($file = readdir($handle)){  //循环读取所有文件
        if($file == '.' || $file == '..'){  //忽略掉 ".",".." 特殊文件夹
            continue;
        }
        $path = $dir.'/'.$file;  //当前文件或文件夹的完整路径
        if(is_dir($path)){  //如果是一个文件夹
            echo '<b>'.$file.'</b><br>';  //输出文件夹名称
            scanDir($path);  //递归遍历子文件夹
        }else{  //如果是一个文件
            echo $file.'<br>';  //输出文件名称
        }
    }
    closedir($handle);  //关闭文件夹
}

In the above sample code, I defined a function scanDir(), which accepts a folder path as a parameter. Inside the function, I first determine whether the incoming path is a folder. If it is not a folder, return directly.

Next, I open the folder and read the files and folders in it in a loop. When traversing to a folder, I output the folder name and recursively call the scanDir() function to traverse the subfolders. When iterating to a file, I just output the file name.

3. scandir() function

PHP also provides a very simple function scandir(), which can be used to obtain a folder at one time All file and folder names under . Different from the opendir() function, this function returns an array that contains the names of all subfolders and files.

Sample code:

$dir = './test';  //文件夹路径
$files = scandir($dir);  //获取文件夹下所有文件和文件夹名称
foreach($files as $file){  //循环遍历
    if($file == '.' || $file == '..'){  //忽略掉 ".",".." 特殊文件夹
        continue;
    }
    echo $file.'<br>';  //输出文件或文件夹名称
}

In the above sample code, I called the scandir() function to get all the file and folder names under the folder, and looped This array is traversed. Likewise, I ignored the two special folders "." and ".." and only output the names of the folders and files.

Summary

In this article, I introduced how to implement folder traversal with PHP and demonstrated three different ways. Through the opendir() and readdir() functions, we can loop through all files and folders in a folder and perform corresponding operations by judging the file type. Through recursive traversal, we can traverse all subdirectories and files in a directory. Through the scandir() function, we obtain all subfolders and file names under a folder at once. If you need to iterate through folders in PHP, I hope this article can provide you with some reference.

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