Character elemental function. Give a parameter as char-length to interface? - function

Question

The question is why i get an error saying the integer charlen is a real when i pass it as the length definition of a character elemental function. To be more specific, the folowing MWE works:
program chararr
implicit none
!!
integer,parameter :: charlen = 20
!!
interface
character(len=20) elemental function adjR(a)
character(len=*),intent(in) :: a
end function
end interface
!!
character(charlen) :: test(3), testR(3)
test = ["hej", "hoj", "haj"]
testR = adjR(test)
print*, test
print*, testR
end program
character(20) elemental function adjR(a)
character(len=*),intent(in) :: a
adjR = adjustr(a)
end function
but the line integer,parameter :: charlen = 20 does nothing. When i change the function and interface definitions like this
character(len=charlen) elemental function adjR(a)
i get the following error:
charmin.f90:7:14:
character(len=charlen) elemental function adjR(a)
1
Error: Expression at (1) must be of INTEGER type, found REAL
UPDATE
The solution of Alexander is in code:
charmin.f90:
program chararr
use char_mod, only: charlen, adjR
implicit none
!!
!interface
!character(30) elemental function adjR(a)
!character(len=*),intent(in) :: a
!end function
!end interface
!!!
character(charlen) :: test(3), testR(3)
test = ["hej", "hoj", "haj"]
testR = adjR(test)
print*, test
print*, testR
print*, charlen !!! it is here
end program
char_mod.f90:
module char_mod
implicit none
integer,parameter :: charlen = 30
private
public charlen, adjR
contains
character(charlen) elemental function adjR(a)
implicit none
character(len=*),intent(in) :: a
adjR = adjustr(a)
end function
end module
To compile:
gfortran -c char_mod.f90
gfortran charmin.f90 char_mod.f90 -o program

Answer 1

charlen is defined in the scope of the program, but the function adjR is outside that scope. Consequently, charlen is not accessible, and since the function does not have implicit none defined, it is interpreted as a real variable.
One solution to this would be to put adjR in a module, and make charlen a module variable.