cpp/named req/FormattedInputFunction

Requirements
A is a stream input function that performs the following:


 * Constructs an object of type with automatic storage duration and with the  argument set to, which performs the following
 * if or  are set on the input stream, sets the  as well, and if exceptions on  are enabled in this input stream's exception mask, throws.
 * flushes the tie'd output stream, if applicable
 * if flag is set on this input stream, extracts and discards characters from the input stream until one of the following becomes true:
 * the next available character on the input stream is not a whitespace character, as tested by the std facet of the locale currently imbued in this input stream. The non-whitespace character is not extracted.
 * the end of the stream is reached, in which case and  are set and if the stream is on for exceptions on one of these bits,  is thrown.


 * Checks the status of the sentry by calling, which is equivalent to.
 * If the sentry returned or sentry's constructor threw an exception, no input takes place
 * If the sentry returned, performs the input as if by calling or.
 * if the end of the stream is reached (the call to or  returns ), sets . If exceptions on  are enabled in this stream's exception mask, throws.
 * if an exception is thrown during input, sets in the input stream. If exceptions on  are enabled in this stream's exception mask, the exception is also rethrown.
 * If no exception was thrown, returns.


 * In any event, whether terminating by exception or returning, the sentry's destructor is called before leaving this function.

Standard library
The following standard library functions are s.


 * , when called on the return value of std
 * , when called on the return value of std
 * , when called on the return value of std
 * , when called on the return value of std
 * , when called on the return value of std
 * , when called on the return value of std