Coder's Guild Mailing List

Re: using rand for cplus

Posted by Morgan Terry on 1999-10-04

an easy way to do it is to just put 
	srand(time(NULL));
at the top of your function.  Remember to include time.h so you can use
the time() function.  

example:

#include <iostream.h>
#include <stdlib.h>
#include <time.h>	// for time() function

int main(void)
{
	int num;
	
	srand(time(NULL));

	cout << "Here is a random number: " << rand();
	
	return 0;
}

this will give you a more random sequence of numbers.  It uses the
current time as a seed to the random number function.

Stormbringer wrote:
> 
> Hi!
> 
> If you get the system date, and use it to seed your rand() function, it will
> guarantee a different result every time.
> 
> I did it in a project a while ago, but I don't remember what the code was
>  I think it was getdate() or something, but don't quote me on that one) ,...
> but  a very loose interpretation ( in "sort-of pseudo code" ) would be:
> 
> function
> {
>     get system date
>     call rand or srand with variable storing system date as argument
> }
> 
> int main
> {
>       call function
>       use rand or srand in your program.
> }
> 
> Wow! How cryptic was that?? If you need a better explanation of that, please
> let me know,... I'll try to explain it a little better....  :)
> 
> Good Luck
> Tammi
> Programmer Analyst
> stormbringr@xxxxxxxxx.xxx
> 
> -----Original Message-----
> From: P oins <poins@xxxxxxxxxx-xxxx.xxx>
> To: stormbringr@xxxxxxxxx.xxx <stormbringr@xxxxxxxxx.xxx>
> Date: Saturday, October 02, 1999 10:11 PM
> Subject: using rand for cplus
> 
> >I need help using the rand and srand functions for c++
> >
> >I'm trying to have a different sequence of numbers come out every time,
> this is what I have but it doesn't work
> >
> >int main()
> >{
> >
> >rnumber=rand();
> >
> >}
> >
> >now when I run this it'll give me the same sequence over and over what I'm
> trying to really ask is How to use the srand function so that i can get a
> different sequence of numbers each time
> >
> >
> >_____________________________________________________________
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> >> >
> 
> > 

-- 
Morgan
morgan@xxxxxxxxxxx.xxx

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