【C++】利用析構統計函數運行時間

#include <iostream>
#include <sys/time.h>

using namespace std;

class TimeUse {
public:
	TimeUse(string name):_name(name) {
		gettimeofday(&_time_begin, NULL);
	}
	~TimeUse() {
		gettimeofday(&_time_end, NULL);
		size_t time_used = (_time_end.tv_sec * 1000 * 1000 + _time_end.tv_usec) - (_time_begin.tv_sec * 1000 * 1000 + _time_begin.tv_usec);
		cout << "Label : " << _name << "\tTime used : " << time_used << "us" << endl;
	}
private:
	struct timeval _time_begin;
	struct timeval _time_end;
	string _name;
};

int sum(int num) {
	int result = 0;
	for(int i=1; i<num; i++){
		result += i;
	}
	return result;
}

long long multiply(int num){
	long long result = 0;
	for(int i=1; i<num; i++) {
		result *= i;
	}
	return result;
}

int main(int argc, char const *argv[]) {
	(TimeUse("Test1"), sum(10000000));
	(TimeUse("Test2"), sum(50000000));
	(TimeUse("Test3"), sum(100000000));
	(TimeUse("Test4"), sum(500000000));
	//(TimeUse("Test5"), multiply(10000));
	//(TimeUse("Test6"), multiply(50000));
	return 0;
}