Solving FORTRAN Array Error w/ Code Sample

[fys iks!]

Hi, I am beginning to learn FORTRAN and am a bit confused with the error i am getting. Here is my code:

program main

IMPLICIT NONE

integer :: limit

WRITE(*,*) "Please enter limit: "
READ(*,*) limit

integer :: allnums(limit)
!
! do i=1,limit
!
! allnums(i) = 0
!
! end do

end program main


all i am trying to do is create an interger array that is the "limit" long. when trying to compile i get the error:

main.f90:10.25:

integer :: allnums(limit)
1
Error: Unexpected data declaration statement at (1)


any ideas?

thanks

 

[bigfooted]

When the size of the array is unknown at compile time, use allocatable arrays.

program main

IMPLICIT NONE

integer :: limit
integer,allocatable :: allnums(:)

WRITE(*,*) "Please enter limit: "
READ(*,*) limit
allocate(allnums(limit))
!
! do i=1,limit
!
! allnums(i) = 0
!
! end do
deallocate(allnums)
end program main

 

[gsal]

Yes...the main point being...you cannot just declare variables anywhere in the program...all declarations need to be done upfront

 

[Mark44]

Yes...the main point being...you cannot just declare variables anywhere in the program...all declarations need to be done upfront

Meaning, before (above) any executable statement, such are WRITE ..., READ ..., and so on.

 

[LudusRex]

Hi there, it looks like the error is occurring because you are trying to declare an integer array within your main program. In FORTRAN, arrays need to be declared outside of the main program, usually in a separate module or subroutine. Here's an example of how you could declare and initialize your array:

program main

IMPLICIT NONE

integer :: limit
integer :: allnums(limit)

! Declare a subroutine to initialize the array
subroutine initialize_array(array, size)
integer, dimension(size) :: array
integer :: size
integer :: i
do i=1,size
array(i) = 0
end do
end subroutine initialize_array

WRITE(*,*) "Please enter limit: "
READ(*,*) limit

! Call the subroutine to initialize the array
call initialize_array(allnums, limit)

end program main

I hope this helps! Good luck with your learning.