std::boolalpha, std::noboolalpha

Defined in header <ios>
std::ios_base& boolalpha( std::ios_base& str );
std::ios_base& noboolalpha( std::ios_base& str );
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.


str - reference to I/O stream

Return value

str (reference to the stream after manipulation).


#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';
    // boolalpha parse
    bool b1, b2;
    std::istringstream is("true false");
    is >> std::boolalpha >> b1 >> b2;
    std::cout << '\"' << is.str() << "\" parsed as " << b1 << ' ' << b2 << '\n';


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

See also

clears the specified ios_base flags
sets the specified ios_base flags
provides the string to use as the name of the boolean true and false
(virtual protected member function of std::numpunct<CharT>)

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