Php file directory operation implementation program (1/2)

II. Directory operations

First, we will introduce a function that reads data from a directory, such as opendir (), readdir (), and closedir (). When using this function, we will first open the file handle and then list it through iteration:

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<? Php $ 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 under the file directory that are already in the Directory (0 files will return false ).

If you need to know the directory information, you can use dirname ($ path) and basename ($ path) to return the directory and file name respectively. disk_free_space ($ path) is available) returns the free space of the viewing space.

Create Command:

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Mkdir ($ path, 0777)

, 0777 is the permission code, which can be set by the umask () function in a non-window environment.

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Rmdir ($ path)

The file with the path in $ path will be deleted.

The dir -- directory class is also an important class for operating file directories. It has three methods: read, rewind, and close. This is an object-oriented class. It first uses open file handles, and then read it by pointer ., see the php manual here:

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<? Php $ 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

File attributes are also very important. File attributes include creation time, last modification time, owner, file Group, type, size, and so on.

Next we will focus on file operations.

III. File operations

● Read files

The first is to check whether a file can be read (Permission problem) or whether the file exists. We can use the is_readable function to obtain information .:

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<? Php $ File = 'dirlist. Php '; If (is_readable ($ file) = false ){ Die ('file does not exist or cannot be read '); } Else { Echo 'exist '; } ?>

The file_exists function is used to determine the existence of the file (as shown below), but this is obviously not comprehensive. It can be used when a file exists.

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<? Php $ 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 in earlier versions. You can create a handle for the file and then read all with pointers:

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$ Fso = fopen ($ cacheFile, 'r '); $ Data = fread ($ fso, filesize ($ cacheFile )); Fclose ($ fso );

There is also a way to read binary files:

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$ Data = implode ('', file ($ file ));

● Write files

The same way as reading files, let's see if it can be written:

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<? Php $ File = 'dirlist. Php '; If (is_writable ($ file) = false ){ Die ("I'm a chicken feather, I can't "); } ?>

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

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<? Php $ File = 'dirlist. Php '; If (is_writable ($ file) = false ){ Die ('I am a chicken feather, I can't '); } $ Data = 'I am cool, I want '; File_put_contents ($ file, $ data ); ?>

File_put_contents functions newly introduced functions in php5 (if you do not know the existence, use the function_exists function to judge first) are unavailable in lower versions of php. You can use the following method:

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

Replaced.

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

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Function cache_page ($ pageurl, $ pagedata ){ If (! $ Fso = fopen ($ pageurl, 'w ')){ $ This-> warns ('cache file cannot be opened. '); // trigger_error Return false; } If (! Flock ($ fso, LOCK_EX) {// LOCK_NB, locking $ This-> warns ('unable to lock the cache file. '); // trigger_error Return false; } If (! Fwrite ($ fso, $ pagedata) {// write byte stream, serialize writes to other formats $ This-> warns ('unable to write the cache file. '); // trigger_error Return false; } Flock ($ fso, LOCK_UN); // release lock Fclose ($ fso ); Return true; }

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