变更的函数

使用 NULL 作为参数调用 set_error_handler() 将重置错误处理程序。
当使用 NULL 调用 set_error_handler() 和 set_exception_handler() 时，现在分别返回上一个错误或异常处理程序。
pack() 和 unpack() 使用 “a”和“A”格式代码时的行为有所变化。 Detailed notes on these changes are available.

MessageFormatter::format() 及其相关函数现在 related functions now accept named arguments and mixed numeric and named arguments when PHP is linked to ICU 4.8 or later.
MessageFormatter::format() and related functions no longer error when an insufficient number of arguments have been provided. Instead, the placeholders will not be substituted.
MessageFormatter::format() and MessageFormatter::parse() are no longer limited to second precision when dealing with times.
IntlDateFormatter::__construct() and datefmt_create() now accept IntlTimeZone and DateTimeZone objects for the timezone argument, and IntlCalendar objects for the calendar argument. Furthermore, if the time zone is omitted and the calendar doesn't specify a time zone, PHP's default time zone from date_default_timezone_get() is now used instead of the default ICU time zone.
IntlDateFormatter::getCalendar() and datefmt_get_calendar() return false if the IntlDateFormatter object was created with an IntlCalendar instance instead of one of the IntlDateFormatter constants.
除 IntlDateFormatter 常量之外， IntlDateFormatter::setCalendar() 和 datefmt_set_calendar()现在接受 IntlCalendar 对象。
IntlDateFormatter::format() 和 datefmt_format() 现在接受 IntlCalendar 对象。