通过

operator>>

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template<class E, class T, class A>
    basic_istream<E, T>& operator>>(
        basic_istream <E, T>& is,
        const basic_string<E, T, A>& str);

The template function overloads operator>> to replace the sequence controlled by str with a sequence of elements extracted from the stream is. Extraction stops:

  • At end of file.
  • After the function extracts is.width() elements, if that value is nonzero.
  • After the function extracts is.max_size() elements.
  • After the function extracts an element c for which use_facet< ctype<E> >( getloc()). is( ctype<E>::space, c) is true, in which case the character is put back.

If the function extracts no elements, it calls setstate(ios_base::failbit). In any case, it calls width(0) and returns *this.

See the related sample program.