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Ciro Santilli 六四事件 法轮功 bf1ca6460d c++: copyfmt
2019-11-13 00:00:00 +00:00

34 lines
724 B
C++

// 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("");
}