Can one .PHP file edit another?

Question

So I have a file for constants. I want to let user define them and then edit my .php filr with that global constants (not xml - real PHP file )

With such code for exampl

Answer 1

You can open the file

$lines = file('myConstants.php');

Edit the content and than save it back

$myFile = 'myConstants.php'
$fh = fopen($myFile, 'w') or die("can't open file");
fwrite($fh, 'DATA HERE');
fclose($fh);