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

Question

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Restore the state of std::cout after manipulating it
(9 answers)
Closed 4 years ago.
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

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.

Answer 2

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 3

You can use the ios::fill() function to set and restore the fill character instead.
http://www.cplusplus.com/reference/iostream/ios/fill/
#include <iostream>
using namespace std;
int main () {
char prev;
cout.width (10);
cout << 40 << endl;
prev = cout.fill ('x');
cout.width (10);
cout << 40 << endl;
cout.fill(prev);
return 0;
}

Answer 4

You can manually change the setfill flag to whatever you need it to be:
float number = 4.5;
cout << setfill('-');
cout << setw(11) << number << endl; // --------4.5
cout << setfill(' ');
cout << setw(11) << number << endl; // 4.5

Answer 5

The null character will reset it back to the original state:
setfill('\0')