23.4: Example
- Page ID
- 54398
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In order to generate different random number for successive executions, the seed must be initialized with a different set of seed values each time.
The following example simulates the roll of two dice, which requires two random integer numbers, each between 1 and 6.
program diceRoll
implicit none
integer :: m, die1, die2, pair
real :: x
integer :: i, n, clock
integer, dimension(:), allocatable :: seed
character(10) :: nickname
call random_seed(size = n)
allocate(seed(n))
call system_clock(count=clock)
seed = clock + 37 * (/(i-1, i=1, n)/)
call random_seed(put = seed)
deallocate(seed)
call random_number(x)
die1 = int(x*6.0) + 1
call random_number(x)
die2 = int(x*6.0) + 1
write (*,'(2(a,1x,i1/),a,1x,i2)') "Dice 1:", die1, &
"Dice 2:", die2, "Dice Sum", (die1+die2)
end program diceRoll
Will generate different values each execution. For example, three executions of the example program are shown below:
C:\fortran> dice Dice 1: 5 Dice 2: 4 Dice Sum 9 C:\fortran> dice Dice 1: 2 Dice 2: 4 Dice Sum 6 C:\fortran> dice Dice 1: 1 Dice 2: 6 Dice Sum 7 C:\fortran>
The dice values will be different for each execution.