Example tutorial on php directory and file operations

1. Directory operation The first is the function to read from the directory, opendir(), readdir(), closedir(). When used, the file handle is opened first, and then iteratively listed:

$base_dir= "filelist/";
$fso=opendir($base_dir);
echo $base_dir."";
while($flist=readdir($fso)){
 echo $flist."< br/>";
}
closedir($fso)
?>

This is a program that returns the files and directories under the file directory (0 files will return false).

Sometimes you need to know the information of the directory. You can use dirname($path) and basename($path) to return the directory part and file name part of the path respectively. You can use disk_free_space($path) to return the remaining space of the view space.

Create command: mkdir($path,0777): 0777 is the permission code, which can be set with the umask() function under non-window conditions. rmdir($path): will delete the file with the path in $path.

2. File operation

New file First, determine the permissions of the directory where the file you want to create is located; the recommended device is 777. Then, it is recommended to use an absolute path for the name of the new file.

$filename="test.txt";
$fp=fopen("$filename", "w+"); //Open the file pointer and create the file
if ( !is_writable( $filename) ){
 die("File:" .$filename. "Not writable, please check!");
}
//fwrite($filename, "anything you want to write to $filename.";
fclose ($fp); //Close the pointer

Read file The first is to check whether a file can be read (permission issue), or whether it exists. We can use the is_readable function to obtain the information.:

$file = 'dirlist.php';
if ( is_readable($file) == false) {
 die('File does not exist or cannot be read');
} else {
 echo 'Exists';
}
?>

Judge file The existing function also includes file_exists (demonstrated below), but this is obviously not as comprehensive as is_readable. When a file exists, it can be used

$file = "filelist.php";
if (file_exists ($file) == false) {
 die('File does not exist');
}
$data = file_get_contents($file);
echo htmlentities($data);
?>

But the file_get_contents function is not supported on lower versions. You can first create a handle to the file and then use the pointer to read all:

There is another way to read binary files: $data = implode('', file($file));

Write files In the same way as reading a file, first check if it can be written:

$file = 'dirlist.php';
if (is_writable($file) == false) {
 die("You have no right to write!");
}
?>

If you can write, you can use the file_put_contents function to write:

$file = 'dirlist.php';
if (is_writable($file) == false) {
 die('I am a chicken feather, I can't');
}
$ data = 'I am despicable, I want';
file_put_contents ($file, $data);
?>

file_put_contents function is a newly introduced function in php5 (if you don’t know it exists, use function_exists The function should be judged first) The lower version of PHP cannot be used. You can use the following method:

$f = fopen($file, 'w');
fwrite($f, $data);
fclose($f);

Replace it.

When writing a file, sometimes you need to lock it, and then write:

function cache_page($pageurl,$pagedata){
 if(!$fso=fopen($pageurl,'w')){
 $this->warns('Unable to open cache file.') ;//trigger_error
 return false;
 }
 if(!flock($fso,LOCK_EX)){//LOCK_NB, exclusive lock
 $this->warns('Unable to lock cache file.');// trigger_error
 return false;
 }
 if(!fwrite($fso,$pagedata)){//Write byte stream, serialize writes other formats
 $this->warns('Unable to write cache file.' );//trigger_error
 return false;
 }
 flock($fso,LOCK_UN);//Release lock
 fclose($fso);
 return true;
}

Copy, delete files Deleting files in PHP is very easy, just use the unlink function:

$file = 'dirlist.php';
$result = @unlink ($file);
if ($result == false) {
 echo 'The mosquitoes were driven away';
} else {
 echo 'Can't get rid';
}
?>

.

Copy files:

$file = 'yang.txt';
$newfile = 'ji.txt'; # The parent folder of this file must be writable
if (file_exists($file) == false ) {
 die ('The demo is not online and cannot be copied');
}
$result = copy($file, $newfile);
if ($result == false) {
 echo 'Copy memory ok';
}
?>

You can use the rename() function to rename a folder. Other operations can be achieved by combining these functions.

Get file attributes

Let me talk about a few common functions: Get the last modified time:

$file = 'test.txt';
echo date('r', filemtime($file));
?>

returned Speaking of Unix timestamps, this is commonly used in caching technology.

Relevant are also getting the last access time fileatime(), filectime() when the file permissions, owner, all groups or other metadata in the inode are updated, the fileowner() function returns the file owner $owner = posix_getpwuid(fileowner($file)); (non-window system), ileperms() obtains file permissions,

$file = 'dirlist.php';
$perms = substr(sprintf('%o', fileperms($file)), -4);
echo $perms;
 ?>

filesize() returns the file size in bytes:

// Output is similar: somefile.txt: 1024 bytes
$filename = 'somefile.txt';
echo $filename . ': ' . filesize($filename) . ' bytes';
?>

To get all the information of the file, there is a function stat() function that returns an array:

$file = 'dirlist.php';
$perms = stat($file);
 var_dump($perms);
?>

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