Php File Operations

PHP File Operations Jamshid Hashimi Trainer, Cresco Solution http://www.jamshidhashimi.com jamshid@netlinks.af @jamshidhashimi ajamshidhashimi Afghanistan Workforce Development Program

Agenda • Introduction • Creating a File • Opening a File – fopen() • Reading From a File – fgets() • Writing to File – fwrite() • Removing File – unlink() • Appending Data • File Locking – flock()

Agenda • Uploading Files via an HTML Form • Getting File Information • More File Functions • Directory Functions • Getting a Directory Listing

Introduction • Manipulating files is a basic necessity for serious programmers and PHP gives you a great deal of tools for creating, uploading, and editing files. • This is one of the most fundamental subjects of server side programming in general. Files are used in web applications of all sizes.

Creating a File • In PHP the fopen function is used to open files. However, it can also create a file if it does not find the file specified in the function call. So if you use fopen on a file that does not exist, it will create it, given that you open the file for writing or appending. $ourFileName = "testFile.txt"; $ourFileHandle = fopen($ourFileName, 'w') or die("can't open file"); fclose($ourFileHandle);

Opening a File • The fopen() function is used to open files in PHP. <?php $file = fopen("welcome.txt", "r") or exit("Unable to open file!"); fclose($file);

Reading From a File • The fgets() function is used to read a single line from a file. <?php $file = fopen("welcome.txt", "r") or exit("Unable to open file!"); //Output a line of the file until the end is reached while(!feof($file)) { echo fgets($file). "<br>"; } fclose($file);

Writing to a File • We can use php to write to a text file. The fwrite function allows data to be written to any type of file. $myFile = "testFile.txt"; $fh = fopen($myFile, 'w') or die("can't open file"); $stringData = "Kabul is the capitaln"; fwrite($fh, $stringData); $stringData = "Samangan is a provincen"; fwrite($fh, $stringData); fclose($fh);

Removing File • In PHP you delete files by calling the unlink function. $myFile = "testFile.txt"; unlink($myFile);

Appending Data $myFile = "testFile.txt"; $fh = fopen($myFile, 'a') or die("can't open file"); $stringData = "New Stuff 1n"; fwrite($fh, $stringData); $stringData = "New Stuff 2n"; fwrite($fh, $stringData); fclose($fh);

File Locking • The key problem with file system operations is the situation you are in if two scripts attempt to write to a file at the same time. • The fopen() function, when called on a file, does not stop that same file from being opened by another script.

File Locking • LOCK_SH to acquire a shared lock (reader). • LOCK_EX to acquire an exclusive lock (writer). • LOCK_UN to release a lock (shared or exclusive). $fp = fopen( $filename,"w"); // open it for WRITING ("w") if (flock($fp, LOCK_EX)) { // do your file writes here flock($fp, LOCK_UN); // unlock the file } else { // flock() returned false, no lock obtained print "Could not lock $filename!n"; }

Uploading Files via an HTML Form • With PHP, it is possible to upload files to the server. <!DOCTYPE html> <html> <body> <form action="upload.php" method="post" enctype="multipart/form-data"> <label for="file">Filename:</label> <input type="file" name="file" id="file"><br> <input type="submit" name="submit" value="Submit"> </form> </body> </html>

Uploading Files via an HTML Form <?php if ($_FILES["file"]["error"] > 0) { echo "Error: " . $_FILES["file"]["error"] . "<br>"; } else { echo "Upload: " . $_FILES["file"]["name"] . "<br>"; echo "Type: " . $_FILES["file"]["type"] . "<br>"; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB<br>"; echo "Stored in: " . $_FILES["file"]["tmp_name"]; }

Uploading Files via an HTML Form ; Maximum allowed size for uploaded files. upload_max_filesize = 40M ; Must be greater than or equal to upload_max_filesize post_max_size = 40M

Directory Functions • scandir() • getcwd() <?php print_r(scandir(”projects")); ?> <?php echo getcwd(); ?>

Directory Functions • chdir() – The chdir() function changes the current directory to the specified directory. <?php //Get current directory echo getcwd(); echo "<br />"; //Change to the images directory chdir(”projects"); echo "<br />"; echo getcwd();

Php File Operations

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