note 81325 modified in function.fopen by danbrown

If you open a file with r+ and execute an fwrite(), writing less to the file than what it originally was, it will result in the difference being padded with the end of the file from the previous end of the file. Example: <?php // Open file for read and string modification $file = "/test"; $fh = fopen($file, 'r+'); $contents = fread($fh, filesize($file)); $new_contents = str_replace("hello world", "hello", $contents); fclose($fh); // Open file to write $fh = fopen($file, 'r+'); fwrite($fh, $new_contents); fclose($fh); ?> If the end of the file was "abcdefghij", you will notice that the difference in "hello world" and "hello", 6 characters, will be appended to the file, resulting in the new ending: "efghij". To obviate this, fopen() with +w instead, which truncates the file to zero length. --was-- If you open a file with r+ and execute an fwrite(), writing less to the file than what it originally was, it will result in the difference being padded with the end of the file from the previous end of the file. Example: <? // Open file for read and string modification $file = "/test"; $fh = fopen($file, 'r+'); $contents = fread($fh, filesize($file)); $new_contents = str_replace("hello world", "hello", $contents); fclose($fh); // Open file to write $fh = fopen($file, 'r+'); fwrite($fh, $new_contents); fclose($fh); ?> If the end of the file was "abcdefghij", you will notice that the difference in "hello world" and "hello", 6 characters, will be appended to the file, resulting in the new ending: "efghij". To obviate this, fopen() with +w instead, which truncates the file to zero length. http://php.net/manual/en/function.fopen.php