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std::boolalpha, std::noboolalpha - cppreference.com

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Defined in header <ios>

std::ios_base& boolalpha( std::ios_base& str );

 (1)

std::ios_base& noboolalpha( std::ios_base& str );

 (2)

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.

Parameters

str - reference to I/O stream

Return value

str (reference to the stream after manipulation).

Example

#include <iostream>
#include <sstream>

int main()
{
    // boolalpha output
    std::cout << "default true: " << true << '\n'
              << "default false: " << false << '\n'
              << std::boolalpha 
              << "boolalpha true: " << true << '\n'
              << "boolalpha false: " << false << '\n'
              << std::noboolalpha 
              << "noboolalpha true: " << true << '\n'
              << "noboolalpha false: " << false << '\n';

    // boolalpha parse
    bool b1, b2;
    std::istringstream is("true false");
    is >> std::boolalpha >> b1 >> b2;

    std::cout << '"' << is.str() << "\" parsed as: "
              << std::boolalpha << b1 << ' ' << b2 << '\n';
}

Output: 

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

See also