std::boolalpha, std::noboolalpha

< cpp‎ | io‎ | manip
Input/output manipulators
Floating-point formatting
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Status flags manipulation
Time and money I/O
Quoted manipulator
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.


[edit] Parameters

str - reference to I/O stream

[edit] Return value

str (reference to the stream after manipulation).

[edit] 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';


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

[edit] See also

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