Easily measure elapsed time

Question

I am trying to use time() to measure various points of my program.

What I don't understand is why the values in the before and after are the same? I understand this is not the best way to profile my program, I just want to see how long something take.

printf("**MyProgram::before time= %ld\n", time(NULL));  doSomthing(); doSomthingLong();  printf("**MyProgram::after time= %ld\n", time(NULL)); 

I have tried:

struct timeval diff, startTV, endTV;  gettimeofday(&startTV, NULL);   doSomething(); doSomethingLong();  gettimeofday(&endTV, NULL);   timersub(&endTV, &startTV, &diff);  printf("**time taken = %ld %ld\n", diff.tv_sec, diff.tv_usec); 

How do I read a result of **time taken = 0 26339? Does that mean 26,339 nanoseconds = 26.3 msec?

What about **time taken = 4 45025, does that mean 4 seconds and 25 msec?

Answer 1

//***C++11 Style:*** #include <chrono>  std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now(); std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();  std::cout << "Time difference = " << std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count() << "[µs]" << std::endl; std::cout << "Time difference = " << std::chrono::duration_cast<std::chrono::nanoseconds> (end - begin).count() << "[ns]" << std::endl;