how to put bitset into a string in c 2b 2b

1#include <iostream>
2#include <bitset>
3int main()
4{
5    std::bitset<8> b(42);
6    std::cout << b.to_string() << '\n'
7              << b.to_string('*') << '\n'
8              << b.to_string('O', 'X') << '\n';
9}