If I turn off magic_quotes in an environment where I did not wrote the code, how can I check if any problems may occur? For what do I have to check? Which functions may not work any more?
When magic_quotes turned on, Magic Quotes automatically performs an addslashes() on all form data submitted. It means that a [\] is placed before every ['], ["], [], or null in the data, so That's nice will be converted to That\'s nice automatically. This all happens before your coding even sees that data, so if you're just passing a string to the next page (not to database) it will print with slashes even though you may not want them at all.