Set/Unset boolalpha format flag
  boolalpha sets the format flag to insert/extract bool objects as names (true or false).
  noboolalpha unsets this flag, being bool objects inserted/extracted as standard integer values.

Parameters.

str

Stream object where to apply. This is a manipulator parameter.

Return Value.
  A reference to the stream object.

Example.

// modify boolalpha flag
#include <iostream>
using namespace std;

int main () {
  bool b;
  b=true;
  cout << boolalpha << b << endl;
  cout << noboolalpha << b << endl;
  return 0;
}

See also.
  flags, setf, unsetf
  ios_base class