[tab:format.type.int]
to_chars(first, last, value, 2); the base prefix is 0b.
The same as b, except that the base prefix is 0B.
Copies the character static_cast<charT>(value) to the output.
Throws format_error if value is not in the range of representable values for charT.
to_chars(first, last, value).
to_chars(first, last, value, 8); the base prefix is 0 if value is nonzero and is empty otherwise.
to_chars(first, last, value, 16); the base prefix is 0x.
The same as x, except that it uses uppercase letters for digits above 9 and the base prefix is 0X.