对于C++的I/O流和各自的缓冲区的理解

#include 
#include 
using namespace std;

int main()
{
        ostream hexout(cout.rdbuf());
        hexout.setf(ios::hex, ios::basefield);
        hexout.setf(ios::showbase);

        hexout << "hexout: " << 177 << " ";
        //cout << "cout: " <<177 << " ";
        //hexout << endl;
        cout << endl;

        istream hexin(cin.rdbuf());
        hexin.setf(ios::hex, ios::basefield);
        hexin.setf(ios::showbase);

        int x;
        hexin >>x;
        cout << x <

hexout: 0xb1 
F
15