Set format flags
  Sets the format flags specified by parameter mask.
  Behaves as a call to stream's member:   setf(mask);
  You must include <iomanip> to use this manipulator.

Parameters.

mask

Mask representing the flags to be set.
This is an object of type ios_base::fmtflags.

Return Value.
  Unspecified.
  This function should only be used as a stream manipulator.

Example.

// setiosflags example
#include <iostream>
#include <iomanip>
using namespace std;

int main () {
  cout << hex << setiosflags (ios_base::showbase);
  cout << 100 << endl;
  return 0;
}

See also.
  resetiosflags
  iomanip manipulators