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PHP creates files (folders) and directory operation codes_PHP tutorial
PHP creates files (folders) and directory operation codes_PHP tutorial
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 $flist."
";
}
closedir($fso)
?>
This is a program that returns the files and directories under the file directory (0 files will return false).
Yes When you need to know the directory information, 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 by the umask() function under non-window conditions.
rmdir($path): will delete the file with the path in $path.
Two , File operations
● Create new files
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 pointer
● Reading a file
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('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(' File does not exist');
}
$data = file_get_contents($file);
echo htmlentities($data);
?>
But file_get_contents function It is not supported on lower versions. You can create a handle to the file first, and then use a pointer to read the entire file:
There is also a way to read binary files:
$data = implode('', file($file));
● Write file
In the same way as reading a file, first check if it can be written:
< ?php
$file = 'dirlist.php';
if (is_writable($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, I can't ');
}
$data = 'I am despicable, I want';
file_put_contents ($file, $data);
?>
The file_put_contents function is a newly introduced function in php5 (if you don’t know it exists, use the function_exists function to determine it first). It cannot be used in lower versions of PHP. 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, 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 write Other formats
$this->warns('Unable to write to cache file.');//trigger_error
return false;
}
flock($fso,LOCK_UN);//Release the lock
fclose($fso);
return true;
}
● Copy and delete files
It is very easy to delete files in php, use the unlink function:
$file = 'dirlist.php';
$ result = @unlink ($file);
if ($result == false) {
echo 'The mosquitoes were driven away';
} else {
echo 'Cannot be driven away';
}
?>
That’s it.
Copying files is also easy:
$file = 'yang.txt';
$newfile = 'ji.txt'; # The parent folder of this file must be writable
if (file_exists($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 latest modification time:
$file = 'test.txt';
echo date('r', filemtime ($file));
?>
The returned timestamp is the unix timestamp, which is commonly used in caching technology.
Related is also getting the last time fileatime was accessed (), filectime() When the file's 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,
< ;?php
$file = 'dirlist.php';
$perms = substr(sprintf('%o', fileperms($file)), -4);
echo $perms;
?>
filesize() returns the number of bytes of the file size:
// 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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