String '?? 54 '(length = 8) What function can be converted to the int type? Solution

String '?? 54 '(length = 8) What function can be converted to the int type? We hope that the converted value is still 54. I have tried intval and int, but none of them will work. after conversion, they will all become int0 ., It is estimated that the bom header var_dump (substr ($ str, 6);, $ s = base64_decode ('77u/77u/string '?? 54 '(length = 8) What function can be converted to the int type?
I hope the converted value is still 54. I have tried intval and int, but none of them work. after conversion, they all become int0.

------ Solution --------------------
It is estimated that the bom header is used.
Var_dump (substr ($ str, 6 ));
------ Solution --------------------
$ S = base64_decode ('77u/77u/NTU = ');
Var_dump ($ s );

Print_r (unpack ('H * ', $ s ));


String (8 )"?? 55"
Array
(
[1] => efbbbf Efbbbf3535
)

Efbbbf is the BOM header for UTF-8 encoded files.

Is your data captured?