lst-0021-book.cpp
// https://godbolt.org/z/4MY1Yznv9
#include <iostream>
using std::cout; using std::endl;
int main() {
int val = 255;
std::ios::fmtflags ff = std::cout.flags();
cout.flags(std::ios::hex | std::ios::showbase);
cout << val << endl; // Output: 0xff
cout.flags(ff);
cout << val << endl; // Output: 255
}