PHP Increment a counting variable in a text file

Question

This seems simple but I can\'t figure it out.

file_get_contents(\'count.txt\');
$variable_from_file++;
file_put_contents(\'count.txt\', $variable_from_file);         


        

Answer 1

If you want to be sure no increments go uncounted (which is what CodeCaster is referring to, the script may load count.txt, increment it, while another file is doing the same, then save that, and then only one increment would have been done and not the proper two), you should use fopen.

$fp = fopen('count.txt', 'c+');
flock($fp, LOCK_EX);

$count = (int)fread($fp, filesize('count.txt'));
ftruncate($fp, 0);
fseek($fp, 0);
fwrite($fp, $count + 1);

flock($fp, LOCK_UN);
fclose($fp);

This will lock the file, preventing any others from reading or writing to it while the count is incremented (meaning others would have to wait before they can increment the value).