std::setiosflags (an abbreviation of 'set input/output stream flags') is a stream modifier.
#include <iomanip> #include <iostream> int main() { const double x = 12.34; std::cout << std::setiosflags(std::ios::scientific) << x << '\n' << std::setiosflags(std::ios::fixed) << x << '\n'; }
Screen output: