Re: Function Timer in C

"James Kanze" <>
10 Apr 2007 02:20:50 -0700
On Apr 9, 4:11 am, "Siddhartha Gandhi" <>

On Apr 6, 1:06 am, "Jim Langston" <> wrote:

<> wrote in message

I have a problem with C programming. I want to make function timing
in C, but I don't know how the function or the algorithm. so, I need
your help to giveme information about it. Thanks.. for your
attention... see.. you..

I generally just use clock().

unsigned int Start = clock();
unsigned int End = clock();
std::cout "Elapapsed time: " << End - Start << " ns" << "\n";

Modify to taste. I think it's ms. On my system it's 1/1000 of a secon=


On most systems it is a millisecond.

On all systems, it's CLOCKS_PER_SEC. Other than that, the only
"standard" I know is Posix, which requires a value of 1000000
for CLOCKS_PER_SEC, i.e. microseconds. (Linux is also Posix
conform in this respect.)

I use std::clock() as well,
margin of error of close to 10 milliseconds, though.

Historically, the granularity was the number of ticks. This
certainly isn't the case today, and I don't know of any system
which really gives microsecond granularity. (Historically, on
the first systems I used, CLOCKS_PER_SEC was 50 in Europe, and
60 in America. Which was the granularity.)

James Kanze (GABI Software)
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