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Timing a C program

Started by MrSaturnFan Nov 27, 2005 at 11:37 PM 5 replies 600+ views

Original Post

Nov 27, 2005 at 11:37 PM

I need to be able to time how long certain things took in my program. I tried using the time.h time function...but that only returns a long int in seconds. What I need is something that can time it in milliseconds. And it must be C and not C++.

hh10k

Nov 28, 2005 at 12:30 AM

If Windows is your flavour, check out QueryPerformanceCounter or timeGetTime.

MrSaturnFan

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MrSaturnFan

Nov 28, 2005 at 12:34 AM

Nah, unfortunately it's gotta work in Unix.

dcosborn

Nov 28, 2005 at 12:42 AM

C has the "clock" function in time.h. It "returns the implementation's best approximation to the processor time used by the program..." (7.23.2.1). There's also a macro called CLOCKS_PER_SEC which gives the frequency of the time returned by clock(). It probably depends on the implementation what sort of frequency you can expect.

nsto119

Nov 28, 2005 at 1:02 AM

http://www.cplusplus.com/ref/ctime

kadaf

Nov 28, 2005 at 1:30 AM

The following code should work on both windows and unix, and has a precission of 1 ms:

#include <sys/timeb.h>...double get_ms_time(void) {        #if defined(WIN32) && (defined(_MSC_VER) || defined(__MINGW32__))                struct _timeb tb;                _ftime(&tb);        #else                struct timeb tb;                ftime(&tb);        #endif        return ((double)tb.time) + ((double)tb.millitm) / 1000.0f;              }

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