What file is favoritevideo? Directory, detailed discussion of file operations—PHP

Reprinted from blueidea.com
1. Introduction
In any computer equipment, files are necessary objects, and in web programming, file operations have always been a headache for web programmers, and file operations are in cms This is necessary and very useful in the system. We often encounter operations such as generating file directories and editing files (folders). Now I will make a detailed summary of these functions in PHP and demonstrate how to use them with examples. About the corresponding functions For a detailed introduction, please refer to the PHP manual. Here we only summarize the key points and points that need attention. (This is not found in the PHP manual.)
2. Directory operation
The first thing we introduce is a function that reads from a directory, opendir( ), readdir(), closedir(), when used, open the file handle first, and then list it iteratively:
$base_dir = "filelist/";
$fso = opendir($base_dir);
echo $base_dir."

---

" ;
while($flist=readdir($fso)){
echo $flist."
" ;
}
closedir($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 directory information, you can use dirname($path) and basename($path) to return the path respectively. For the directory part and file name part, disk_free_space($path) can be used to return the free space.
Creation command:
mkdir($path,0777)
,0777 is the permission code, which can be set by the umask() function under non-window .
rmdir($path)
will delete the file with the path in $path.
dir -- The directory class is also an important class for operating file directories. It has three methods, read, rewind, and close. This is a pseudo-object-oriented class. , it first uses a file handle to open, and then reads it using a pointer. See the php manual here:
$d = dir("/etc/php5");
echo "Handle: " . $d->handle . "n";
echo "Path: " . $d->path . "n";
while (false !== ($entry = $d->read()) ) {
echo $entry."n";
}
$d->close();
?>
Output:
Handle: Resource id #2
Path: /etc/php5
.
..
apache
cgi
cli
The attributes of files are also very important. File attributes include creation time, last modification time, owner, file group, type, size, etc.
Let’s focus on file operations below.
3. File operations
Read files
First, 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('The file does not exist or cannot be read');
} else {
echo 'Exists';
}
?>
The function to determine the existence of a file also includes file_exists (demonstrated below), But this is obviously not as comprehensive as is_readable. When a file exists, you can use
$file = "filelist.php";
if (file_exists($file) == false) {
die('The file does not exist
Read all:
$fso = fopen($cacheFile, 'r');
$data = fread($fso, filesize($cacheFile));
fclose($fso);
There is another way to read Binary file:
$data = implode('', file($file));
Writing a file
Same as reading a file, first check if it can be written:
$file = ' dirlist.php';
if (is_writable($file) == false) {
die("I am a chicken feather, I can't");
}
?>
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 if it exists, use the function_exists function to check it first). Lower versions of php cannot be used, but you can Use the following method:
$f = fopen($file, 'w');
fwrite($f, $data);
fclose($f);
Replace it.
Sometimes you need to lock when writing a file, and then Write:
function cache_page($pageurl,$pagedata){
if(!$fso=fopen($pageurl,'w')){
$this->warns('Cannot open cache file.');// trigger_error
return false;
}
if(!flock($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 the lock
fclose($fso);
return true;
}
Copy and delete files
It is very easy to delete files with php, use the unlink function to operate simply:
$file = 'dirlist.php';
$result = @unlink ($file);
if ($result == false) {
echo 'The mosquitoes were driven away';
} else {
echo 'Can't be driven away' ;
}
?>
That’s it.
Copying files is also easy:
$file = 'yang.txt';
$newfile = 'ji.txt'; # The parent folder of this file must be Can write
if (file_exists($file) == false) {
die ('The sample 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 latest modification time:
$file = 'test.txt';
echo date('r', filemtime($file));
?>
Return Speaking of Unix timestamps, this is commonly used in caching technology.
Related are also getting the time last accessed fileatime(), filectime() when the file's permissions, owner, all groups or other metadata in the inode are Update time, the fileowner() function returns the file owner
$owner = posix_getpwuid(fileowner($file));
(non-window system), ileperms() gets the 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 a file, there is a function stat() that returns an array:
$file = 'dirlist.php';
$perms = stat($file);
var_dump($perms);
? >
You can check the detailed information about what the key corresponds to, which will not be expanded here.
IV. Conclusion
I briefly summarized several file operations above. If you are proficient in the functions listed above, you will already be operating. There is no big problem. The function of PHP file operation changes quickly and is now very powerful. The file part is also a very important part of learning PHP. I hope you will not ignore it.

The above introduces what file and directory favoritevideo is, and a detailed discussion of file operations - PHP, including what file favoritevideo is. I hope it will be helpful to friends who are interested in PHP tutorials.