std::boolalpha, std::noboolalpha

 

C++

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streamoff

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Input/output manipulators

Floating-point formatting
showpointnoshowpoint setprecision	fixedscientifichexfloatdefaultfloat (C++11)(C++11)
Integer formatting
setbase showbasenoshowbase	dechexoct
Boolean formatting
boolalphanoboolalpha
Field width and fill control
setfill setw	internalleftright
Other formatting
showposnoshowpos	uppercasenouppercase
Whitespace processing
ws ends	skipwsnoskipws
Output flushing
flush endl flush_emit (C++20)	unitbufnounitbuf emit_on_flushnoemit_on_flush (C++20)(C++20)
Status flags manipulation
resetiosflags	setiosflags
Time and money I/O
get_money (C++11) get_time (C++11)	put_money (C++11) put_time (C++11)
Quoted manipulator
quoted (C++14)

 

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

Run this code

#include <iostream>#include <sstream>   int main(){// boolalpha outputstd::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 parsebool 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

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