Why one backslash is changed into two?

[a123123]

I have problem with this code:

<?php
$patterns = array('/(?<=\s)(\s|,|\+|frac|cdot|begin|cases|end|\^|\(|\)|\[|\]|\{|\}|\d|\-|\=|(?<=\+|\-|\=)(a|e|i|o|u|y)|b|c|d|f|g|h|j|k|l|m|n|p|r|s|t(?!ex)|(?<!te)x|B|C|D|F|G|H|J|K|L|M|N|P|R|S|T|X|.\(.\)|^\[t\]|^\[\/t\])+(?=(\s|,|\.|\?|\!|\(??!\[\/tex\]).|\n)*\[t\])/');
$replacements = array('($1)');
$string=$_POST['kod'];
echo preg_replace($patterns, $replacements, $string);
?>

Why it changes one backslash: \ into two: \\?

Thanks for answer.

[.josh]

php is probably configured to have magic quotes enabled.  You can check by using get_magic_quotes_gpc.  If it returns true, use stripslashes() to remove it  (see the example and user notes in the get_magic_quotes_pgc() entry)

[a123123]

It was very helpless for me, I've done it and the problem is solved thank you very much

 

sorry for my English

 

where I can mark that the topic is solved? I remember that here used to be such an option