serialize

$sites = array('Google', 'Runoob', 'Facebook');
$serialized_data = serialize($sites);   
// a:3:{i:0;s:6:"Google";i:1;s:6:"Runoob";i:2;s:8:"Facebook";} 

unserialize

$un = unserialize($str);

大致类型

a - array
b - boolean
d - double
i - integer
o - common object
r - reference
s - string
C - custom object
O - class
N - null
R - pointer reference
U - unicode string
N - NULL