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std::showbase, std::noshowbase

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< cpp‎ | io‎ | manip
Revision as of 15:56, 2 November 2012 by P12bot (Talk | contribs)

Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <ios>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
std::ios_base& showbase( std::ios_base& str );
</td>

<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">

<td >
std::ios_base& noshowbase( std::ios_base& str );
</td>

<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end

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.

Contents

Parameters

str - reference to I/O stream

Return value

str (reference to the stream after manipulation)

Example

#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

Template:cpp/io/manip/dcl list resetiosflagsTemplate:cpp/io/manip/dcl list setiosflags