New Parameters

Several functions were given new, optional parameters in PHP 5.4:

PHP Core:

• Added optional argument to debug_backtrace() and debug_print_backtrace() to limit the amount of stack frames returned
• is_a() and is_subclass_of() now have third boolean parameter, which specifies if the first argument can be a string class name.

OpenSSL:

• Added no padding option to openssl_encrypt() and openssl_decrypt()

Intl:

• idn_to_ascii() and idn_to_utf8() now take two extra parameters, one indicating the variant (IDNA 2003 or UTS #46) and another, passed by reference, to return details about the operation in case UTS #46 is chosen.