C++ iomanip Library - setiosflags Function


The C++ function std::setiosflags behaves as if member setf were called with mask as argument on the stream on which it is inserted/extracted as a manipulator (it can be inserted/extracted on input streams or output streams).

It is used to sets the format flags specified by parameter mask.


Following is the declaration for std::setiosflags function.

 setiosflags (ios_base::fmtflags mask);


mask − Mask representing the flags to be set. fmtflags is a bitmask type.

Return Value

It returns unspecified. This function should only be used as a stream manipulator.


Basic guarantee − if an exception is thrown, the stream is in a valid state.

Data races

The stream object on which it is inserted/extracted is modified. Concurrent access to the same stream object may introduce data races.


In below example explains about setiosflag function.

#include <iostream>
#include <iomanip>

int main () {
   std::cout << std::hex;
   std::cout << std::setiosflags (std::ios::showbase | std::ios::uppercase);
   std::cout << 100 << std::endl;
   return 0;

Let us compile and run the above program, this will produce the following result −