如何避免在每個子例程中聲明和設置變量的值？

Question

如何避免重複聲明子程序中具有常量值的變量？

例如：

program test 

implicit none 

integer :: n 

integer :: time 

print*, "enter n" ! this will be a constant value for the whole program 

call Calcul(time) 

print*, time 

end program 

subroutine Calcul(Time) 

implicit none 

integer :: time 

! i don't want to declare the constant n again and again because some times the subroutines have a lot of variables. 

time = n*2 

end subroutine 

有時候也有很多是由用戶定義的，我會賺很多使用這些常量子程序的常數，所以我想炒股他們，並利用它們而不是一次又一次地重新定義它們。

Answer 1

對於全局變量，使用模塊（舊FORTRAN使用公共塊，但他們已經過時）：

module globals 
    implicit none 

    integer :: n 

contains 

    subroutine read_globals() !you must call this subroutine at program start 

    print*, "enter n" ! this will be a constant value for the whole program 
    read *, n 
    end subroutine 
end module 

!this subroutine should be better in a module too !!! 
subroutine Calcul(Time) 
    use globals !n comes from here 
    implicit none 

    integer :: time 
    time = n*2 
end subroutine 

program test 
    use globals ! n comes from here if needed 
    implicit none 

    integer :: time 

    call read_globals() 

    call Calcul(time) 

    print*, time 
end program 

有很多的問題和答案，解釋如何在Stack Overflow上正常使用的Fortran模塊。