FORTRAN Open Arbitrary number of files in Do Loop

[minger]

I have a quick question that I've always wondered exactly how to do but never needed to. Well of course now I do. I have a DO loop that loops an arbitrary number of times. I would like to open a file each time it comes around, using the DO loop iterator as part of the filename. Ideally, it would look something like...

n = 5
DO i=1,n
 OPEN(11,file='input000',i,'.fmt',form='formatted')
 blah blah blah
 CLOSE(11)
END DO

So, if anyone knows how to parse the variable into that text string, I would appreciate it. Thanks,

 

[mathmate]

I do not know what version of Fortran you run, but this example should be close to what you can do.

      IMPLICIT INTEGER(I-N), REAL*8(A-H,O-Z)
      N=5
      CHARACTER *10 FN
      DO 5 I=1,N
      WRITE(FN,10)I
      WRITE(6,*)FN
      OPEN(1,FILE=FN)
      CLOSE(1)
    5 CONTINUE
   10 FORMAT(5HINPUT,I3.3)
      STOP
      END

The screen output looks like this, and the corresponding files have been opened (and closed):

INPUT001
INPUT002
INPUT003
INPUT004
INPUT005

 

[minger]

BTW, I'm using FORTRAN90. I get that and it'll get me 90% there. How can I then add a '.fmt' as a file extension? I imagine the period needs some special character designation?

Thanks,

 

[mathmate]

You only have to add the suffix at the end of the format statement, and don't forget to inccrease the length of FN to 12, as follows:

      IMPLICIT INTEGER(I-N), REAL*8(A-H,O-Z)
      N=5
      CHARACTER *12 FN
      DO 5 I=1,N
      WRITE(FN,10)I
      WRITE(6,*)FN
      OPEN(1,FILE=FN)
      CLOSE(1)
    5 CONTINUE
   10 FORMAT('INPUT',I3.3,'.FMT')
      STOP
      END

I believe the translation to F90 should be trivial.

 

[minger]

Beautiful; working. Thanks a bunch!

 

[mathmate]

Glad that everything works out!

 

[mitramatra]

Hi everyone

I have got similar problem..

How can i write to an existing file without deleting previous data.

so basically i want to add new info every time i run the program.


Thanks

 

[minger]

Try using

ENDFILE

http://docs.hp.com/en/B3908-90002/ch08s06.html?btnNext=next%A0%BB

 

[mathmate]

Open the file with the keyword 'append', for example:

OPEN(1, FILE='mydata.dat', ACCESS='APPEND')