PHP directory operations and file operations _php tutorial

In any computer device, files are all necessary objects, and in Web programming, the operation of the file has always been a headache for web programmers, and, the operation of the file in the CMS system is a must, very useful, we often encounter generating files directory, file (clip) editing operations, Now I have a detailed summary of these functions in PHP and examples of how to use them. For a detailed description of the corresponding function, please refer to the PHP manual. Here are just a few things to focus on. And where to pay attention. (This is not in the PHP manual.)

Second, directory operation

The first introduction is a function read from the directory, Opendir (), Readdir (), Closedir (), using the file handle is opened first, and then the iteration is listed:

$base _dir = "filelist/"; $fso = Opendir ($base _dir); echo $base _dir. " " ; while ($flist =readdir ($FSO)) { echo $flist. " " ; } Closedir ($FSO) ?>

This is the return file directory under which the file is already in the directory program (0 file will return false).

Sometimes you need to know the directory information, you can use DirName ($path) and basename ($path), respectively, return the directory portion of the path and the file name part, the Disk_free_space ($path) to return to see space free space.

To create a command:

mkdir ($path, 0777)

, 0777 is the permission code, the Umask () function can be set under non-window

RmDir ($path)

The path to the $path file will be deleted.

DIR--The Directory class is also an important class to manipulate the file directory, there are 3 methods, Read,rewind,close, this is a copy object-oriented class, it first uses the open file handle, and then read by the way of the pointer. Here's a look at the PHP manual:

$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 properties of the file are also very important, including the creation time, the last modified time, the owner, the file group, the type, the size, and so on.

Here we focus on file operations.

Third, file operation

A, read the file

The first is a file to see if it can read (permission problems), or there is no, we can use the Is_readable function to obtain information.

$file = ' dirlist.php '; if (is_readable ($file) = = False) { Die (' file does not exist or cannot be read '); } else { echo ' presence '; } ?>

The function of judging the existence of a file is also file_exists (shown below), but this is obviously not is_readable comprehensive. 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); ?>

However, the file_get_contents function is not supported on earlier versions, you can create a handle to the file first, and then read all with the pointer:

$fso = fopen ($cacheFile, ' R '); $data = Fread ($fso, FileSize ($cacheFile)); Fclose ($FSO);

There is also a way to read a binary file:

$data = Implode (', File ($file));

B, write the file

and read the file the same way, first see if it can write:

$file = ' dirlist.php '; if (is_writable ($file) = = False) { Die ("I'm chicken feathers, I can't"); } ?>

If you can write it, you can use the File_put_contents function to write:

$file = ' dirlist.php '; if (is_writable ($file) = = False) { Die (' I'm chicken feathers, I can't '); } $data = ' I am contemptible, I want to '; File_put_contents ($file, $data); ?>

file_put_contents function in the php5 of the newly introduced function (do not know the existence of the function_exists function first to judge) the lower version of PHP is not available, you can use the following way:

$f = fopen ($file, ' w '); Fwrite ($f, $data); Fclose ($f);

Replace it.

When writing a file, you sometimes need to lock 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 type lock $this->warns (' cannot lock cache file. '); /trigger_error return false; } if (!fwrite ($fso, $pagedata)) {//write byte stream, serialize write to other format $this->warns (' cannot write to cache file. '); /trigger_error return false; } Flock ($fso, lock_un);//Release lock Fclose ($FSO); return true; }

C, copy, delete files

PHP Delete Files is very easy, with the unlink function simple operation:

$file = ' dirlist.php '; $result = @unlink ($file); if ($result = = False) { Echo ' Mosquitoes have driven away '; } else { Echo ' cannot be driven away '; } ?>

Can.

Copying files is also easy:

$file = ' yang.txt '; $newfile = ' ji.txt '; # The parent folder of this file must be able to write if (file_exists ($file) = = False) { Die (' sample not online, cannot copy '); } $result = Copy ($file, $newfile); if ($result = = False) { echo ' Copy memory OK '; } ?>

You can use the rename () function to rename a folder. The other operations are done by combining these functions.

D. Get file attributes

I say a few common functions:

Gets the last modified time:

$file = ' test.txt '; echo Date (' R ', Filemtime ($file)); ?>

Returns a timestamp that says Unix, which is commonly used in caching techniques.

Related to the last time accessed Fileatime (), Filectime () when the permissions of the file, the owner, the metadata in all groups or other inode are updated, 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 number of bytes in the file size:

Output similar to: somefile.txt:1024 bytes $filename = ' somefile.txt '; Echo $filename. ': ' . FileSize ($filename). ' bytes '; ?>

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

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

The key corresponds to what can be consulted in detail, which is not expanded here.

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