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std::boolalpha, std::noboolalpha

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< cpp‎ | io‎ | manip
Revision as of 05:28, 23 April 2013 by P12 (Talk | contribs)

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<td>
Defined in header <ios>
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<td></td> <td></td> <tr class="t-dcl ">

<td >
std::ios_base& boolalpha( std::ios_base& str );
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<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">

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

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

2) disables the boolalpha flag in the stream str as if by calling str.unsetf(std::ios_base::boolalpha)

std::boolalpha is an I/O manipulator, so it may be called with an expression such as out << std::boolalpha for any out of type std::basic_ostream or with an expression such as in >> std::boolalpha 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>
int main()
{
    // boolalpha output
    std::cout << std::boolalpha 
              << "boolalpha true: " << true << '\n'
              << "boolalpha false: " << false << '\n';
    std::cout << std::noboolalpha 
              << "noboolalpha true: " << true << '\n'
              << "noboolalpha false: " << false << '\n';
    // booalpha parse
    bool b1, b2;
    std::istringstream is("true false");
    is >> std::boolalpha >> b1 >> b2;
    std::cout << '\"' << is.str() << "\" parsed as " << b1 << ' ' << b2 << '\n';
}

Output:

boolalpha true: true
boolalpha false: false
noboolalpha true: 1
noboolalpha false: 0
"true false" parsed as 1 0

See also

Template:cpp/io/manip/dcl list resetiosflagsTemplate:cpp/io/manip/dcl list setiosflagsTemplate:cpp/locale/numpunct/dcl list do truefalsename