Measure time to execute a piece of code

[saurabh.ss]

Hi
I want to measure the time required to execute a piece of code.
For example, I want to know the time required to execute a given
function. How do I do it within C++? I know I got to use a library
called ctime. But I dont know what functions to use. Please tell me.

 

[MadhavC]

I want to measure the time required to execute a piece of code.
For example, I want to know the time required to execute a given
function. How do I do it within C++? I know I got to use a library
called ctime. But I dont know what functions to use. Please tell me.

include time.h in your C++ file

clock_t start, finish;
start = clock();

// your code here

finish = clock();

( (finish - start)/CLOCKS_PER_SEC )
should give the time taken by your code

~Madhav

 

[saurabh.ss]

include time.h in your C++ file

clock_t start, finish;
start = clock();

// your code here

finish = clock();

( (finish - start)/CLOCKS_PER_SEC )
should give the time taken by your code

~Madhav

But this gives time in seconds, right? My execution time may be in
milliseconds (or even less). The code you gives 0 time for all
executions. Is there a method to obtain greater resolution?

 

[b.evrim]

I reccomend you to use this class:
http://oldmill.uchicago.edu/~wilder/Code/timer/
It is pretty simple and easy to use. I have used it in a lot of my code
snippets, works very well. It is time resolution is also high.

 

[MadhavC]

But this gives time in seconds, right? My execution time may be in
milliseconds (or even less). The code you gives 0 time for all
executions. Is there a method to obtain greater resolution?

simply don't devide by CLOCKS_PER_SEC
(finish - start) will give you the CPU clocks occured in between.
And I am not sure if sombody can get time detailed to less than the CPU
clock

~Madhav

 

[MadhavC]

I reccomend you to use this class:
http://oldmill.uchicago.edu/~wilder/Code/timer/
It is pretty simple and easy to use. I have used it in a lot of my code
snippets, works very well. It is time resolution is also high.

I don't see the resolution of this "class" is below 1 sec.
Am I missing something?

~Madhav

 

[Gerard Kramer]

If you are on a unix flavour, perhaps a util named gprof is useful. It
gives you detailed information, including time spent at a particular
function, number of calls, etc.

I suppose (?) other systems have something similar.

 

[Jerry Coffin]

@y41g2000cwy.googlegroups.com>, (e-mail address removed)
says...

[ ... ]

( (finish - start)/CLOCKS_PER_SEC )

Try using:

(double(finish - start)/CLOCKS_PER_SEC)

and you may find the results somewhat more useful.

 

[bitkidoku]

It works as the way you explained but it is compact and has a couple of
more features. I didnt used it in a year but I remember it's resolution
is below 1 sec. And I looked at the code and I dont see a reason for
resolution to be 1 sec. Am I missing something too? (Maybe one of us
should try to execute the sample )