HERE is another using <time.h> file
its sequence will always be unique
#include<time.h>
#include<stdio.h>
int main()
{
time_t t;
int i;
srand(time(&t));
i=rand()%1000;
printf("%d",i);
return 0;
}
On Sat, Jun 26, 2010 at 11:15 AM, Pushparaj Shetty <[email protected]>wrote:
> Hi,
> Thank you very much. It worked fine. I had to include the necessary header
> files.
>
> On Fri, Jun 25, 2010 at 8:52 PM, Sharad Birmiwal <[email protected]
> > wrote:
>
>> On Fri, Jun 25, 2010 at 10:03 AM, Pushparaj Shetty <[email protected]>
>> wrote:
>> > Hi,
>> > I need to generate random number to assign weights to graph edges. Using
>> > rand() will give same random sequence on every run. Kindly tell how to
>> > generate distinct random for every run.
>> > In Borland C there is randomize()? whats is the equivalent here?
>>
>> You can use srand(unsigned int seed) to choose the randomization seed,
>> if that's what you want. To get a unique random sequence every time
>> you start your application, this is what I'd suggest (this is what I
>> do, a dirty hack):
>>
>> (I'm writing this on the spur of the moment, just take the idea and
>> code it yourself);
>>
>> unsigned int seed;
>> fd=open("/dev/random", RD_ONLY);
>> read(fd, &seed, sizeof(seed));
>> close(fd);
>> srand(seed);
>>
>>
>> What this approach essentially does is take the seed from this file
>> called "/dev/random". From the name, I have always guessed that
>> everytime you read /dev/random, it generates random input.
>>
>> What I hope is happening is that "/dev/random" gets affected by
>> "noisy" inputs like frequency of keyboard usage, mouse behaviour etc
>> (these things are not unheard of, may be they happen if you have the
>> hardware generators). This random sequence generator might also be
>> taking inputs like variation in CPU temperature or disk usage to
>> "truly" randomize itself.
>>
>> On a side note, one resource you might want to dig into is random
>> number generation by gnu scientific library (gsl)[1].
>>
>>
>> Hope this helps,
>> Sharad
>>
>>
>> [1]
>> http://www.gnu.org/software/gsl/manual/html_node/Random-Number-Generation.html
>>
>>
>> --
>> l...@iitd - http://tinyurl.com/ycueutm
>>
>
>
>
> --
> Pushparaj Shetty D.
> IIT Delhi
> Cell# 9716616748
>
> --
> l...@iitd - http://tinyurl.com/ycueutm
>
--
Kumar Anurag
--
l...@iitd - http://tinyurl.com/ycueutm
