Ответ 1
std::cout << std::setw(5) << std::setfill('0') << std::internal << -5 << '\n';
// ^^^^^^^^
Вывод:
-0005
Edit:
Для тех, кто заботится о таких вещах, N3337 (~c++11
), 22.4.2.2.2
:
The location of any padding is determined according to Table 91.
Table 91 - Fill padding
State Location
adjustfield == ios_base::left pad after
adjustfield == ios_base::right pad before
adjustfield == internal and a
sign occurs in the representation pad after the sign
adjustfield == internal and
representation after stage 1 began
with 0x or 0X pad after x or X
otherwise pad before