<?php
//the original array
$a = array(
'a23' => 'abcdefg
hij'
);
//make it serial
$s = serialize($a);
//just to see the serial string
var_dump($s);
//the serialized array
$s1 = 'a:1:{s:3:"a23";s:11:"abcdefg
hij";}';
//the same with linux line end character
$s2 = "a:1:{s:3:\"a23\";s:11:\"abcdefg\12hij\";}";
//the same with windows line end character, same I had in my PEAR files
$s3 = "a:1:{s:3:\"a23\";s:11:\"abcdefg\15\12hij\";}";
//turn it back to an array
$a1 = unserialize($s1); // ok
$a2 = unserialize($s2); // ok
$a3 = unserialize($s3); // not ok