In any computer device, files are necessary objects, and in web programming, file operations have always been a headache for web programmers. However, file operations in cms systems are Necessary and very useful. 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. For a detailed introduction to the corresponding functions, please Consult 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 Operations
The first thing to introduce is a method of reading from a directory. The functions taken, opendir(), readdir(), closedir(), when used, first open the file handle, 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 about returning the file The files under the directory are already in the 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 directory part of the path respectively. and the file name part, you can use disk_free_space($path) to return the free space.
Creation command:
mkdir($path,0777) |
, 0777 is the permission code, in non- The umask() function can be set under window.
rmdir($path) |
will delete the file with the path in $path. The
dir -- directory class is also an important class for operating file directories. , there are 3 methods, read, rewind, 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:
Path: /etc/php5 . .. apache cgi cli |
$file = 'dirlist.php'; if (is_readable($file) == false) { die('文件不存在或者无法读取'); } else { echo '存在'; } ?> |
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
if (file_exists($file) == false) { die('File does not exist'); } $data = file_get_contents($file ); echo htmlentities($data); ?> |
$fso = fopen($cacheFile, 'r'); $data = fread($fso, filesize($cacheFile)); fclose($fso); |
$data = implode('', file($file)); |
$file = 'dirlist.php'; |
$file = 'dirlist.php'; |
If you can write, you can use the file_put_contents function to write:
$file = 'dirlist.php'; if (is_writable($file) == false) { die('我是鸡毛,我不能'); } $data = '我是可鄙,我想要'; file_put_contents ($file, $data); ?> |
The file_put_contents function is new in php5 The imported function (if you don’t know it exists, use the function_exists function to determine it first) cannot be used in lower versions of PHP. You can use the following method:
$f = fopen($file, 'w'); fwrite($f, $data); fclose($f); |
to 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')){ $this->warns('无法打开缓存文件.');//trigger_error return false; } if(!flock($fso,LOCK_EX)){//LOCK_NB,排它型锁定 $this->warns('无法锁定缓存文件.');//trigger_error return false; } if(!fwrite($fso,$pagedata)){//写入字节流,serialize写入其他格式 $this->warns('无法写入缓存文件.');//trigger_error return false; } flock($fso,LOCK_UN);//释放锁定 fclose($fso); return true; } |
C. Copy and delete files
It is very easy to delete files in PHP. Use the unlink function to simply operate:
$file = 'dirlist.php'; $result = @unlink ($file); if ($result == false) { echo '蚊子赶走了'; } else { echo '无法赶走'; } ?> |
.
Copying files is also easy:
$newfile = 'ji.txt'; # Parent folder of this file Must be able to write if (file_exists($file) == false) { die ('The sample is not online and cannot be copied'); } $result = copy($ file, $newfile); if ($result == false) { echo 'Copy memory ok'; } ?> |
$file = 'test.txt'; |
$file = 'test.txt'; |
Returns the unix timestamp, which is Caching technology is commonly used.
Relevant ones include obtaining the last access time fileatime(), filectime() when the file permissions, owner, all groups or other metadata in the inode are updated, fileowner () function returns the file owner
$owner = posix_getpwuid(fileowner($file)); |
$owner = posix_getpwuid(fileowner($file)); |
$file = 'dirlist.php'; |
$file = 'dirlist.php'; |
// 输出类似:somefile.txt: 1024 bytes $filename = 'somefile.txt'; ?> |
$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.