C++性能测试精确到秒毫秒纳秒include iostream include string include chrono void Run for int i0i1000000000i int main auto beforeTime std chrono steady clock now Run auto afterTime std chrono steady clock now std cout总耗时std endl秒double duration second std chrono duration double afterTime beforeTime.count std cout duration second秒std endl毫秒级double duration millsecond std ch