How can I get the execution time of a program in milliseconds in C?

Question

Currently I\'m getting the execution wall time of my program in seconds by calling:

time_t startTime = time(NULL);
//section of code
time_t         


        

Answer 1

I recently wrote a blog post that explains how to obtain the time in milliseconds cross-platform.

It will work like time(NULL), but will return the number of milliseconds instead of seconds from the unix epoch on both windows and linux.

Here is the code

#ifdef WIN32
#include 
#else
#include 
#include 
#endif

/* Returns the amount of milliseconds elapsed since the UNIX epoch. Works on both
 * windows and linux. */

int64 GetTimeMs64()
{
#ifdef WIN32
 /* Windows */
 FILETIME ft;
 LARGE_INTEGER li;
 uint64 ret;

 /* Get the amount of 100 nano seconds intervals elapsed since January 1, 1601 (UTC) and copy it
  * to a LARGE_INTEGER structure. */
 GetSystemTimeAsFileTime(&ft);
 li.LowPart = ft.dwLowDateTime;
 li.HighPart = ft.dwHighDateTime;

 ret = li.QuadPart;
 ret -= 116444736000000000LL; /* Convert from file time to UNIX epoch time. */
 ret /= 10000; /* From 100 nano seconds (10^-7) to 1 millisecond (10^-3) intervals */

 return ret;
#else
 /* Linux */
 struct timeval tv;
 uint64 ret;

 gettimeofday(&tv, NULL);

 ret = tv.tv_usec;
 /* Convert from micro seconds (10^-6) to milliseconds (10^-3) */
 ret /= 1000;

 /* Adds the seconds (10^0) after converting them to milliseconds (10^-3) */
 ret += (tv.tv_sec * 1000);

 return ret;
#endif
}

You can modify it to return microseconds instead of milliesconds if you want.