php - encoding before/after print -

here example :

echo var_dump(mb_detect_encoding(serialize($criteria), "auto"));   print_r ($criteriarooms);   echo mb_detect_encoding(serialize($criteria), "auto");   

the output :

bool(false)   array(...)   string(5) "ascii"   

anyone can explaintome changing after print_r

the problem script not working without print_r on windows, when ı tried update mysql giving incorrect string value: '\xb4;s:40...' column... , script working fine on centos.

thanx