Time functions on windows

[RipRage]

Hi

are there any windows equivalents to getimeofday() and timersub() ? i have tried GetLocalTime() but the "wSecond" is just in the range 0 to 59 ;-(

Any suggestions

Thanks in advanced.

[hypheni]

"wSecond" is just in the range 0 to 59 ;-(

what do you want ?

[RipRage]

i am calculating a transfer and simply just want to keep track of seconds. e.g obtain start time, then obtain time again after every recv() then do sub-second precision.

If i use GetLocalTime(), assuming i started at eg. 1:30:59, i could receive later at 1:31:00, and end up calculating the transfer took -59 seconds...

[hypheni]

means you want to evaluate the 1:31:00 - 1:30:59 ?

why dont you just add 60 to the result. Here 60 + (-59) = 1sec.

put this in a if statement while wSecond is 0

[zapper222]

Sounds like a perfect use for epoch time.
Check out http://www.epochconverter.com/progra...unctions-c.php

[RipRage]

What about subsecond precision on windows? Are there any functions which can handle this? Like timersub() on unix?

[itsmeandnobodyelse]

What about subsecond precision on windows? Are there any functions which can handle this? Like timersub() on unix?

The precision of a timer call is only about 15 milliseconds. So if you want to measure one single call you probably won't get any difference. You either need to use a high precision timer which is hardware dependent or measure a multiple of the same call, e. g. 100000 times. If doing the latter you normally call GetTickCount() rather then GetLocalTime, where the result already is in milliseconds.

[RipRage]

Thank you for your replies.

I have also seen QueryPerformanceCounter(), is it possible to do sub second precision using this function ? If so can anyone suggest any information on using it.

Many thanks!

[itsmeandnobodyelse]

You might try to call the function passing a pointer to a LARGE_INTEGER variable.

If the returned value is 0 your hardware doesn't support a high performance counter.

static LARGE_INTEGER liempty = { 0 };

LARGE_INTEGER li = { 0 };

if (QueryPerformanceCounter(&li) == FALSE || li == liempty)
{
    // no performance counter available

If the call succeeds the 'li' would get a 64-bit integer which counts the closest ticks the performance counter would support, probably in nanoseconds.

[RipRage]

Ah yes, that's great, many thanks!