// https://cirosantilli.com/linux-kernel-module-cheat#cpp

#include <cassert>

#include <iomanip>

#include <iostream>

#include <sstream>

int main() {

constexpr float pi = 3.14159265359;

std::stringstream ss;

// Sanity check default print.

ss << pi;

assert(ss.str() == "3.14159");

ss.str("");

// Change precision format to scientific,

// and restore default afterwards.

std::ios ss_state(nullptr);

ss_state.copyfmt(ss);

ss << std::setprecision(2);

ss << std::scientific;

ss << pi;

assert(ss.str() == "3.14e+00");

ss.str("");

ss.copyfmt(ss_state);

// Check that cout state was restored.

ss << pi;

assert(ss.str() == "3.14159");

ss.str("");

}