Operators for struct timeval

time_example.cpp

#include <iostream>
#include <stdlib.h>
#include <sys/time.h>
#include "timeval_operators.h"	

using namespace std;

int main(int argc, char* argv[])
{
	timeval t0, t1;

	gettimeofday(&t0, NULL);
	for (int i = 0; i < 1000000; i++);
	gettimeofday(&t1, NULL);
	cout << (t1 - t0) << endl;

	return 0;
}

timeval_operators.h

#ifndef TIMEVALOPERATORS_H
#define TIMEVALOPERATORS_H

using namespace std;

// ********** struct timeval: overloaded operators **********

// ***** output *****

inline ostream& operator<<(ostream& out,struct timeval tv)
{
	out << "sec: " << tv.tv_sec << " usec: " << tv.tv_usec;
	return out;
}

// ***** comparison *****
inline bool operator<(struct timeval t0,struct timeval t1)
{
	return
	 t0.tv_sec < t1.tv_sec ||
	 t0.tv_sec == t1.tv_sec && t0.tv_usec < t1.tv_usec;
}
inline bool operator<=(struct timeval t0,struct timeval t1)
{
	return
	 t0.tv_sec < t1.tv_sec ||
	 t0.tv_sec == t1.tv_sec && t0.tv_usec <= t1.tv_usec;
}
inline bool operator==(struct timeval t0,struct timeval t1)
{
	return t0.tv_sec == t1.tv_sec && t0.tv_usec == t1.tv_usec;
}
inline bool operator!=(struct timeval t0,struct timeval t1)
{
	return !(t0 == t1);
}
inline bool operator>(struct timeval t0,struct timeval t1)
{
	return !(t0 <= t1);
}
inline bool operator>=(struct timeval t0,struct timeval t1)
{
	return !(t0 < t1);
}

// ***** arithmetic *****
// pre: t0 + t1 representable in a struct timeval
inline struct timeval operator+(struct timeval t0,struct timeval t1)
{
	struct timeval t = {t0.tv_sec+t1.tv_sec,t0.tv_usec+t1.tv_usec};
	if (t.tv_usec >= 1000000) { // carry needed
		t.tv_sec++;
		t.tv_usec -= 1000000;
	}
	return t;
}
// pre: t0 + t1 representable in a struct timeval
inline struct timeval operator+=(struct timeval& t0,struct timeval t1)
{
	t0.tv_sec += t1.tv_sec;
	t0.tv_usec += t1.tv_usec;
	if (t0.tv_usec >= 1000000) { // carry needed
		t0.tv_sec++;
		t0.tv_usec -= 1000000;
	}
	return t0;
}
// pre: t0 >= t1
inline struct timeval operator-(struct timeval t0,struct timeval t1)
{
	struct timeval t = {t0.tv_sec-t1.tv_sec,t0.tv_usec-t1.tv_usec};
	if (t.tv_usec < 0) { // borrow needed
		t.tv_sec--;
		t.tv_usec += 1000000;
	}
	return t;
}
// pre: t0 >= t1
inline struct timeval operator-=(struct timeval& t0,struct timeval t1)
{
	t0.tv_sec -= t1.tv_sec;
	t0.tv_usec -= t1.tv_usec;
	if (t0.tv_usec < 0) { // borrow needed
		t0.tv_sec--;
		t0.tv_usec += 1000000;
	}
	return t0;
}

#endif