#include <stdlib.h> int rand(void);
rand returns pseudorandom numbers in the range from 0 to RAND_MAX.
RAND_MAX is defined as 32767 in <stdlib.h>. The sequence of
pseudorandom numbers is controlled by the value of seed.
You can set this value by a call to srand. You can call srand
at any time to
reset the number generator to a new starting point. The initial default
seed is 1.
rand returns a random number between 0 and 32767.
seed and the exact
range in which values can be generated may vary from implementation to
implementation. (The sequence of numbers produced for a given seed by the
library is the same as the usual UNIX C library implementation.)
The algorithm used for rand in this implementation is described in
the ANSI Standard. The period is 2**32 calls. Because the value v
returned is in the range 0 <. = v <. = 32767,
individual values of v
may be repeated after about 2**16 calls, but the sequence as a whole does
not repeat until 2**32 calls.
#include <stdlib.h>
#include <stdio.h>
main()
{
char card, suit;
/* sets seed to 22 */
srand (22);
/* Assign a random value to card and suit. */
card = "A23456789TJQK"[rand()%13];
suit = "CDHS"[rand()%4];
printf("Your card: %c %cn", card, suit);
}
srand
Copyright (c) 1998 SAS Institute Inc. Cary, NC, USA. All rights reserved.