Convert C code to Delphi -- random function

[Peter Williams]

Hi All,

I need to port the following (small) C language function to Delphi:

double Rand(void) {
return rand()/(1.0 + (double)RAND_MA X);
}

NB -- elsewhere in the program randomize is called before-hand.

I don't know what (exactly) the C language function "rand()" does.
Also, RAND_MAX is not defined anywhere in the program, so is it part of
C ???

My attempt at starting to write it in Delphi:

function Rand : Real;
begin
Result := ??????????????? ?
end;

NB -- Delphi has a Random(N) function which takes an integer (N) as
it's parameter and returns an integer in the range 0..N-1 . E.g.
Random(3) would return either 0, 1, or 2.

NB(2) -- Obviously, Delphi also has a "randomize" function which I am
aware I need to call first.

Can anyone please assist me in writing this routine as a Delphi code
snippet???

Any help will be greatly appreciated. :-)

Regards,
Peter W. :-)))
Sandy Bay, Hobart, Tas, AU.

[Keith Thompson]

Re: Convert C code to Delphi -- random function

"Peter Williams" <pew@bigpond.ne t.au> writes:[color=blue]
> I need to port the following (small) C language function to Delphi:
>
> double Rand(void) {
> return rand()/(1.0 + (double)RAND_MA X);
> }
>
> NB -- elsewhere in the program randomize is called before-hand.
>
> I don't know what (exactly) the C language function "rand()" does.
> Also, RAND_MAX is not defined anywhere in the program, so is it part of
> C ???[/color]

You should be able to find this information in any C textbook or in
your system's documentation, but ...

The rand() function returns a pseudo-random integer in the range 0 to
RAND_MAX.

RAND_MAX is an integer constant defined in <stdlib.h>; its value will
vary from one implementation to another, but it's guaranteed to be at
least 32767.

srand() seeds the random number generator. A given seed will produce
a repeatable sequence of numbers from rand(). If you don't call
srand(), it's equivalent to calling it with a seed value of 1.

The function appears to be attempting to generate a random double
(floating-point) number in the range 0.0 to 1.0, with the upper bound
excluded.

You might take a look at section 13 of the C FAQ,
<http://www.eskimo.com/~scs/C-faq/top.html>.
[color=blue]
> My attempt at starting to write it in Delphi:[/color]
[snip]

Good luck with the Delphi part; we can't help you with it here.

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[pete]

Re: Convert C code to Delphi -- random function

Keith Thompson wrote:[color=blue]
>
> "Peter Williams" <pew@bigpond.ne t.au> writes:[/color]
[color=blue][color=green]
> > double Rand(void) {
> > return rand()/(1.0 + (double)RAND_MA X);
> > }[/color][/color]
[color=blue]
> The function appears to be attempting to generate a random double
> (floating-point) number in the range 0.0 to 1.0, with the upper bound
> excluded.[/color]

And the cast is superfluous.

--
pete