istrstream

class istrstream : public istream {
public:
    explicit istrstream(const char *s);
    explicit istrstream(char *s);
    istrstream(const char *s, streamsize n);
    istrstream(char *s, streamsize n);
    strstreambuf *rdbuf() const;
    char *str();
    };

The class describes an object that controls extraction of elements and encoded objects from a stream buffer of class strstreambuf. The object stores an object of class strstreambuf.