Error Handling Techniques

[javijerome]

Does fortran95 have some error handling techniques like the "try" statement of Visual Basic 2008?

 

[xwb]

Pure Fortran 95 does not have any form of exception handling. There was a proposal in the 1996 X3J3 draft for exception handling but I don't know if it got into 2003.

There are some partial 2003 compilers about but I don't know if there are any full 2003 implementations.

 

[javijerome]

what's the 1996 X3J3 draft?

 

[xwb]

X3J3 is the ANSI committee that looks after the Fortran Standards. You can find the 1996 draft in the following link

http://www.math.bas.bg/bantchev/place/fortran95.pdf

 

[NickFort]

xwb, I think I read the other day somewhere that Cray and IBM compilers can handle the full F2003 set now. Slightly off-topic, but interesting nonetheless.

--------------------------------------
Background: Chemical engineer, familiar mostly with MATLAB, but now branching out into real programming.

 

[mikrom]

I'm not sure, but I thing, there is no general exception handling concept in Fortran, like in OOP-languages:
try..catch (Java), try..except (Python), begin..resccue..end (Ruby)
In Fortran you can handle different exceptions at different ways - for example:
1. file exeption with iostat

  ...
  integer stat
  ...
  ! open file
  open (1, file='csv_file.csv', status='old', iostat=stat)
  if (stat .ne. 0) then
    write(*,*) 'File cannot be opened !'
    go to 99
  end if
  ...
  ! close file
  99 continue
  close(1)

2. Arithmetic exceptions with ieee_arithmetic module

[COLOR=#a020f0]program[/color] exception
[COLOR=#a020f0]use[/color] ieee_arithmetic
[COLOR=#2e8b57][b]implicit[/b][/color] [COLOR=#2e8b57][b]none[/b][/color]

[COLOR=#2e8b57][b]integer[/b][/color], [COLOR=#2e8b57][b]parameter[/b][/color] :: n[COLOR=#804040][b]=[/b][/color][COLOR=#ff00ff]2[/color]
[COLOR=#2e8b57][b]integer[/b][/color] :: k
[COLOR=#2e8b57][b]real[/b][/color] :: x, y(n), z
x [COLOR=#804040][b]=[/b][/color] [COLOR=#ff00ff]1.0[/color]
y [COLOR=#804040][b]=[/b][/color] ([COLOR=#804040][b]/[/b][/color][COLOR=#ff00ff]5.0[/color], [COLOR=#ff00ff]0.0[/color][COLOR=#804040][b]/[/b][/color])
[COLOR=#804040][b]do[/b][/color] k [COLOR=#804040][b]=[/b][/color] [COLOR=#ff00ff]1[/color], n 
  z [COLOR=#804040][b]=[/b][/color] x[COLOR=#804040][b]/[/b][/color]y(k)
  [COLOR=#804040][b]if[/b][/color] (ieee_is_finite(z)) [COLOR=#804040][b]then[/b][/color]
    [COLOR=#804040][b]print[/b][/color] [COLOR=#804040][b]*[/b][/color], [COLOR=#ff00ff]"Z = "[/color], z
  [COLOR=#804040][b]else[/b][/color]
    [COLOR=#804040][b]print[/b][/color] [COLOR=#804040][b]*[/b][/color], [COLOR=#ff00ff]"Error: Z is infinite!"[/color]
  [COLOR=#804040][b]end if[/b][/color]
[COLOR=#804040][b]end do[/b][/color] 
[COLOR=#a020f0]end program[/color] exception

$ g95  exception.f95 -o exception

$ exception
 Z =  0.2
 Error: Z is infinite!

However, I don't know how wide ieee_arithmetic is supported by several compilers, because the above code doesn't compile with gfortran

$ gfortran  exception.f95 -o exception
exception.f95:2.19:

use ieee_arithmetic
                  1
Fatal Error: Can't open module file 'ieee_arithmetic.mod' for reading at (1): No such file or directory
gfortran.exe: Internal error: Aborted (program f951)
Please submit a full bug report.
See <[URL unfurl="true"]http://gcc.gnu.org/bugs.html>[/URL] for instructions.

 

[javijerome]

ieee_arithmetic? was is it? silverfrost's fortran95 compiler brings an error. should i create a module first? or is this module supposed to be predefined?

 

[NickFort]

See what mikrom said:

However, I don't know how wide ieee_arithmetic is supported by several compilers, because the above code doesn't compile with gfortran

Obviously, that isn't supported by Silverfrost's compiler if it gives you an error.

--------------------------------------
Background: Chemical engineer, familiar mostly with MATLAB, but now branching out into real programming.