Fortran 90 creating an array of unknown size

max2112

I was given an assignment to create a program that solves the Josephus Problem ([URL="http://en.wikipedia.org/wiki/Josephus_problem"]. the program needs to work for n amount of people, and it must use an array.

Problem:
I need to create a subroutine that will allow the user to read(*,*) n
and create an array that is n big.

Attempt:

subroutine sub(n)
implicit none
integer :: n, i
integer :: array(n)
do i = 1, n
array(i) = 0
end do
end subroutine sub

program arrays
implicit none

integer :: size, i
write(*,*) "how big is your array"
read(*,*) size
call sub(size)

end program arrays

I am stuck, and dont know why this isnt working.

Mark44

Quote by max2112

I was given an assignment to create a program that solves the Josephus Problem ([URL="http://en.wikipedia.org/wiki/Josephus_problem"]. the program needs to work for n amount of people, and it must use an array.

Problem:
I need to create a subroutine that will allow the user to read(*,*) n
and create an array that is n big.

Attempt:
Mod note: I added a [code] tag at the top of your code, and a [/code] tag at the bottom. You should do that when you post code as it makes your code easier to read, by preserving your indentation.

Code:

subroutine sub(n)
	implicit none
	integer :: n, i
	integer :: array(n)
	do i = 1, n
		array(i) = 0
	end do
end subroutine sub

program arrays
	implicit none

	integer :: size, i
  write(*,*) "how big is your array"
	read(*,*) size
	call sub(size)



end program arrays

I am stuck, and dont know why this isnt working.

Here's a link to an article about arrays in fortran 90 - http://orion.math.iastate.edu/burkar...an_arrays.html. Take a look at the whole article, but especially the section on dynamic arrays.

billiards

Summit like this:

Code:

subroutine(/arguments/)

real,allocatable :: array(:)

/code/

allocate ( array(x) )

/code/

deallocate ( array )

return

Louisa

Quote by max2112

I was given an assignment to create a program that solves the Josephus Problem ([URL="http://en.wikipedia.org/wiki/Josephus_problem"]. the program needs to work for n amount of people, and it must use an array.

Problem:
I need to create a subroutine that will allow the user to read(*,*) n
and create an array that is n big.

Attempt:

subroutine sub(n)
implicit none
integer :: n, i
integer :: array(n)
do i = 1, n
array(i) = 0
end do
end subroutine sub

program arrays
implicit none

integer :: size, i
write(*,*) "how big is your array"
read(*,*) size
call sub(size)

end program arrays

I am stuck, and dont know why this isnt working.

Why do you think that is not working?
You didn't print out anything after the value of "n" is typed.

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billiards	Summit like this: Code: subroutine(/arguments/) real,allocatable :: array(:) /code/ allocate ( array(x) ) /code/ deallocate ( array ) return