C++ - How to reset the output stream manipulator flags [duplicate]

Question

I've got a line of code that sets the fill value to a '-' character in my output, but need to reset the setfill flag to its default whitespace character. How do I do that?

cout << setw(14) << "  CHARGE/ROOM" << endl;
cout << setfill('-') << setw(11) << '-' << "  " << setw(15) << '-' << "   " << setw(11) << '-' << endl;

I thought this might work:

cout.unsetf(ios::manipulatorname) // Howerver I dont see a manipulator called setfill

Am I on the wrong track?

Answer 1

You can use copyfmt to save cout's initial formatting. Once finished with formatted output you can use it again to restore the default settings (including fill character).

{
    // save default formatting
    ios init(NULL);
    init.copyfmt(cout);

    // change formatting...
    cout << setfill('-') << setw(11) << '-' << "  ";
    cout << setw(15) << '-' << "   ";
    cout << setw(11) << '-' << endl;

    // restore default formatting
    cout.copyfmt(init);
}

Answer 2

Have a look at the Boost.IO_State_Savers, providing RAII-style scope guards for the flags of an iostream.

Example:

#include <boost/io/ios_state.hpp>

{
  boost::io::ios_all_saver guard(cout); // Saves current flags and format

  cout << setw(14) << "  CHARGE/ROOM" << endl;
  cout << setfill('-') << setw(11) << '-' << "  " << setw(15) << '-' << "   " << setw(11) << '-' << endl;
// dtor of guard here restores flags and formats
}

More specialized guards (for only fill, or width, or precision, etc... are also in the library. See the docs for details.