std::showbase, std::noshowbase - cppreference.com (original) (raw)
| Defined in header | | | | ---------------------------------------------------------------------------------------------- | --- | | | std::ios_base& showbase( std::ios_base& str ); | (1) | | | std::ios_base& noshowbase( std::ios_base& str ); | (2) | |
Enables the
showbaseflag in the stream str as if by calling str.setf(std::ios_base::showbase).Disables the
showbaseflag in the stream str as if by calling str.unsetf(std::ios_base::showbase).
This is an I/O manipulator, it may be called with an expression such as out << std::showbase for any out of type std::basic_ostream or with an expression such as in >> std::showbase for any in of type std::basic_istream.
The showbase flag affects the behavior of integer output (see std::num_put::put), monetary input (see std::money_get::get) and monetary output (see std::money_put::put).
[edit] Parameters
| str | - | reference to I/O stream |
|---|
[edit] Return value
str (reference to the stream after manipulation).
[edit] Notes
As specifed in std::num_put::put, the showbase flag in integer output acts like the # format specifier in std::printf, which means the numeric base prefix is not added when outputting the value zero.
[edit] Example
#include #include #include #include int main() { // showbase affects the output of octals and hexadecimals std::cout << std::hex << "showbase: " << std::showbase << 42 << '\n' << "noshowbase: " << std::noshowbase << 42 << '\n'; // and both input and output of monetary values std::locale::global(std::locale("en_US.UTF8")); long double val = 0; std::istringstream("3.14") >> std::showbase >> std::get_money(val); std::cout << "With showbase, parsing 3.14 as money gives " << val << '\n'; std::istringstream("3.14") >> std::noshowbase >> std::get_money(val); std::cout << "Without showbase, parsing 3.14 as money gives " << val << '\n'; }
Output:
showbase: 0x2a noshowbase: 2a With showbase, parsing 3.14 as money gives 0 Without showbase, parsing 3.14 as money gives 314