cpp/io/basic istream/operator gtgt2

@1-2@ Performs character input operations.

@1@ Behaves as a. After constructing and checking the sentry object, which may skip leading whitespace, extracts a character and stores it to. If no character is available, sets (in addition to  that is set as required of a ).

@2@ Behaves as a. After constructing and checking the sentry object, which may skip leading whitespace, extracts successive characters and stores them at successive locations of. The extraction stops if any of the following conditions is met:
 * A whitespace character (as determined by the facet) is found. The whitespace character is not extracted.

In either case, an additional null character value is stored at the end of the output. If no characters were extracted, sets (the null character is still written, to the first position in the output). Finally, calls to cancel the effects of std, if any.
 * End of file occurs in the input sequence (this also sets ).

@3@ Calls the appropriate extraction operator, given an rvalue reference to an input stream object (equivalent to ). .

Return value
@1-2@ @3@