NAME¶

std::showbase,std::noshowbase - std::showbase,std::noshowbase

Synopsis¶

Defined in header <ios>
std::ios_base& showbase( std::ios_base& str ); (1)
std::ios_base& noshowbase( std::ios_base& str ); (2)

1) enables the showbase flag in the stream str as if by calling
str.setf(std::ios_base::showbase)

2) disables the showbase flag 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).

Parameters¶

str - reference to I/O stream

Return value¶

str (reference to the stream after manipulation)

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.

Example¶

// Run this code

#include <sstream>
#include <locale>
#include <iostream>
#include <iomanip>
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 is("3.14");
is >> std::showbase >> std::get_money(val);
std::cout << "With showbase, parsing 3.14 as money gives " << val << '\n';
is.seekg(0);
is >> 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

See also¶

resetiosflags clears the specified ios_base flags
(function)
setiosflags sets the specified ios_base flags
(function)