How to BREAK the program with a message when some condition occurs

Question

I am trying to find a way to put a breaking order when some condition occurs in one subroutine of my f90 program. Is it possible to have any ideas from it? the code scheme looks like this:

    /
    modules
    PROGRAM
    allocate variables
    CALL subroutines for initializing variables
    ...
    do 1,max iterations
    CALL subroutine1
    CALL subroutine2
    CALL subroutine3 !--> here I have the condition
    ...
    ...
    end do

    END PROGRAM

    Subroutine subroutine3 
    ...
    if (condition = true) then ! what I want to do here is to break the program printing a message saying that it is stopped because condition is true)

    end if
    end subroutine 3

    /

I would appreciate your help,

I am quite new with fortran and I am new in this forum!

Thank you in advance,

Albert P

Solution

if (condition) stop

will bring your program to a stop immediately. You might prefer

if (condition) then
   write(*,*) 'A friendly message'
   stop
end if

If your compiler is Fortran 2008 compliant you can even write

if (condition) stop 'A friendly message'

However, perhaps what you want to do is not stop your program but exit from the subroutine in which case you would jump to the end of the subroutine, in some acceptable fashion.

Note well that condition=true is not syntactically correct Fortran to compare the value of condition with the logical constant .true.. It is an assignment statement. The syntactically correct comparison would be condition == .true. but that is semantically noxious, simply writing if (condition) expresses everything that if (condition == .true.) does. The abbreviated form also suggests that you are a programmer rather than a script-kiddy.

Comments

[Hristo Iliev]

"The abbreviated form also suggests that you are a programmer rather than a script-kiddy." LOL, made my day! :)

[APuig]

thanks again, I was just putting redundant stuff, I was aware about the 'condition = true'