Stop fortran program with non-zero exit status

fortran exit gfortran exit-code
MvG picture MvG · Jun 30, 2013 · Viewed 19.4k times · Source

I'm adapting some Fortran code I haven't written, and without a lot of fortran experience myself. I just found a situation where some malformed input got silently ignored, and would like to change that code to do something more appropriate. If this were C, then I'd do something like

fprintf(stderr, "There was an error of kind foo");
exit(EXIT_FAILURE);

But in fortran, the best I know how to do looks like

write(*,*) 'There was an error of kind foo'
stop

which lacks the choice of output stream (minor issue) and exit status (major problem).

How can I terminate a fortran program with a non-zero exit status?

In case this is compiler-dependent, a solution which works with gfortran would be nice.

Answer

M. S. B. picture M. S. B. · Jun 30, 2013

The stop statement allows a integer or character value. It seems likely that these will be output to stderr when that exists, but as stderr is OS dependent, it is unlikely that the Fortran language standard requires that, if it says anything at all. It is also likely that if you use the numeric option that the exit status will be set. I tried it with gfortran on a Mac, and that was the case:

program TestStop

integer :: value

write (*, '( "Input integer: " )', advance="no")
read (*, *) value

if ( value > 0 ) then
   stop 0
else
   stop 9
end if

end program TestStop

While precisely what stop with an integer or string will do is OS-dependent, the statement is part of the language and will always compile. call exit is a GNU extension and might not link on some OSes.

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