File Handling with PHP

1. File Handling with PHP

2. Open/Close a File • A file is opened with fopen() as a “stream” • PHP returns a ‘handle’ to the file • Used to reference the open file • Each file is opened in a particular mode • A file is closed with fclose() or when your script ends

3. File Open Modes

4. File Open/Close Example <?php // open and close file to read $toread = fopen(‘some/file.txt’,’r’); fclose($toread); // open and close file to write $towrite = fopen(‘some/file.txt’,’w’); fclose($towrite); ?>

5. Writing Data • To write data to a file use • fwrite($handle,$data) EXAMPLE: $handle = fopen('people.txt', 'a'); fwrite($handle, ‘\nFred:Male'); fclose($handle);

6. But first… • Create the file on the web server • Set permissions to write

7. <?php /* Write to a file http://ned.highline.edu/~tostrander/215/file_io/write.php */ // open file to write $file = fopen('poem.txt', 'w'); $text = "Mama said I'd lose my head if it wasn't fastened on. Today I guess it wasn't 'cause while playing with my cousin it fell off and rolled away and now it's gone. ~ Shel Silverstein"; // write to the file fwrite($file, $text); echo "File created successfully."; // close file fclose($file); ?>

8. Reading Data • There are two main functions to read data: • fgets($handle) • Reads a line of data at a time • fread($handle,$bytes) • Reads up to $bytes of data, stops at EOF (end of file) • Used to read entire file at once

9. fgets() • feof($handle) returns true if we have reached end of file $fileName = "poem.txt"; echo "<h3>Method 1: fgets()</h3>"; // open file to read $file = fopen($fileName, 'r'); // read file contents one line at a time while (!feof($file)) { echo nl2br(fgets($file)); } fclose($file); • nl2br($string) converts new line characters into <br /> tags

10. Delimiters echo "<h3>Method 1: fgets() – Delimiters</h3>"; $fileName = "students.txt"; $file = fopen($fileName, 'r'); while (!feof($file)) { $line = fgets($file); $array = explode("^", $line); $sid = $array[0]; $first = $array[1]; $last = $array[2]; echo "$sid: $first $last<br />"; } fclose($file); students.txt 1^Cheryl^McCalop 2^Laura^Lavell 3^Thu^Trinh

11. fread() $fileName = "poem.txt"; echo "<h3>Method 2: fread()</h3>"; // open file to read $file = fopen($fileName, 'r'); // read file contents all at once $contents = fread($file, 1024); echo nl2br($contents); fclose($file);

12. File Open shortcuts • There are two ‘shortcut’ functions that don’t require a file to be opened • $lines = file($filename) • Reads entire file into an array with each line a separate entry in the array. • $str = file_get_contents($filename) • Reads entire file into a single string.

13. file() $fileName = "poem.txt"; echo "<h3>Method 3: file()</h3>"; // read entire file into an array $lines = file($fileName); foreach($lines as $line) echo nl2br($line);

14. file_get_contents() $fileName = "poem.txt"; echo "<h3>Method 4: file_get_contents()</h3>"; // read entire file into a string $fileString = file_get_contents($fileName); echo nl2br($fileString);

15. Other File Operations • Delete file • unlink('filename'); • Rename (file or directory) • rename('old name', 'new name'); • Copy file • copy('source', 'destination'); • And many, many more • www.php.net/manual/en/ref.filesystem.php

16. Dealing With Directories • Open a directory • $handle = opendir('dirname'); • $handle 'points' to the directory • Read contents of directory • readdir($handle) • Returns name of next file in directory • Files are sorted as on filesystem • Close a directory • closedir($handle) • Closes directory 'stream'

17. Directory Example $handle = opendir('.'); while ($fileName=readdir($handle)) { echo"$fileName<br />"; } closedir($handle);

18. Other Directory Operations • Get current directory • getcwd() • Change Directory • chdir('dirname'); • Create directory • mkdir('dirname'); • Delete directory (MUST be empty) • rmdir('dirname'); • Change directory permissions • chmod('dirname', value); • And more... • www.php.net/manual/en/ref.dir.php

19. Try It Write a script that: • Creates a subdirectory called “sub” in file IO • Creates a file in “sub,” and write some text to the file • Renames the file • Renames the directory • chmod's the file and the directory to 772