Essential PHP File and Directory Functions Guide

1. Check if File or Directory Exists

is_file() Function

• is_file() — Checks if the given filename is a regular file. Returns TRUE if the file exists and is a regular file; otherwise, returns FALSE.
• Official documentation: http://php.net/manual/zh/function.is-file.php

is_dir() Function

• is_dir() — Checks if the specified filename is a directory. Returns TRUE if the file exists and is a directory; otherwise, returns FALSE.
• Official documentation: http://php.net/manual/zh/function.is-dir.php

file_exists() Function

• file_exists() — Checks whether a file or directory exists. Returns TRUE if the specified file or directory exists; otherwise, returns FALSE. This function combines the functionality of the two functions above.
• More information: PHP file_exists() Function

2. Reading Files

file_get_contents() Function

• file_get_contents() — Reads the entire file into a string.
• PHP official usage: http://php.net/manual/zh/function.file-get-contents.php

fread() Function

Example of reading a file:

<?php
 $file = fopen("test.txt","r");
 fread($file,filesize("test.txt"));
 fclose($file);
?>

More usage instructions: PHP fread() Function

3. Writing Files

fwrite() Function

Note: The original text incorrectly labeled this section as fread() again. This section covers writing files using fwrite().

Example:

<?php
 $myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
 $txt = "Bill Gates\n";
 fwrite($myfile, $txt);
 fclose($myfile);
?>

More information: PHP File Creation/Write

file_put_contents() Function

• file_put_contents() — Writes a string to a file. It performs the same function as calling fopen(), fwrite(), and fclose() sequentially.
• Usage: file_put_contents('filename','filedata')
• Official documentation: http://php.net/manual/zh/function.file-put-contents.php

4. Create, Delete, and Copy Directories

mkdir() Function (Create Directory)

• Usage: mkdir('filename','mode'), default mode is 0777 (maximum permissions).
• Return value: Returns TRUE on success or FALSE on failure.
• Official documentation: http://php.net/manual/zh/function.mkdir.php

rmdir() Function (Delete Directory)

• Return value: Returns TRUE on success or FALSE on failure.
• Official documentation: http://php.net/manual/zh/function.rmdir.php

unlink() Function (Delete File)

• Return value: Returns TRUE on success or FALSE on failure.
• Official documentation: http://php.net/manual/zh/function.unlink.php

copy() Function (Copy File)

• Syntax: copy(source,destination)
• Return value: Copies the file from source to destination. Returns TRUE on success or FALSE on failure.
• More information: PHP copy() Function

rename() Function

• rename() — Renames a file or directory.
• Syntax: rename(oldname,newname,context)
• Return value: Returns TRUE on success or FALSE on failure.

move_uploaded_file() Function

• move_uploaded_file() — Moves an uploaded file to a new location.
• Syntax: move_uploaded_file(file,newloc)
• Return value: Returns TRUE on success or FALSE on failure.