Re: A question about g77's OPEN & WRITE

[Toon Moene <toon at moene dot indiv dot nluug dot nl>]

Zhong Wang wrote:

>   I am using g77 for programing now. But I found that
> g77 is somewhat 
> different to Visual Fortran in I/O.
> 
>   In visual fortran, the following code is legal:
> 
>   REAL a(10)
>   OPEN(10,file='aaa.dat',form='binary')
>   WRITE(10)a
>   CLOSE(10)
> <<<<<
>   You can see that in file aaa.dat there's not
> anything between the integer 
> and real numbers.
>   But in g77, if I use:
> 
>   REAL a(10)
>   OPEN(10,file='aaa.dat',form='unformatted')
>   WRITE(10)a
>   CLOSE(10)
> <<<<<
>   With "hexedit aaa.dat", you can find there's a
> length value before and after 
> each record. You know, sometimes we have to make more
> efforts to deal with 
> those length values when we use other softwares to
> open these data files. For 
> example, when I use matlab to open the file, I have to
> read off those length 
> values. It's very convinient.
> 
>   Can you recommend me a possible method with g77 to
> generate data file which 
> contains no extra bytes in it? Or can the developers
> add some new features 
> like form='direct' to g77?

No, there's no method to get rid of the record lenghts in an unformatted
file when using g77.  However, if all the records in your file are the
same length, you could write a "direct access" file, by doing the writes
thusly:

      REAL A(10)
      OPEN(...,ACCESS='DIRECT',RECL=....)
      DO I = 1, N
         ... fill A
         WRITE(...,REC=I) A
      ENDDO
      CLOSE(...)

This will give you a file with N records of length 10 (32-bit words)
without any other data in it.

Hope this helps,

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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