Thank you, Paul, David, Mike, chl and other guys.
I have read the links (and other related links), and it is really
helpful for my puzzels.
And now, I have another problem. (The following are on MS Windows
XP(sp2))
IDL6.0 can not read data saved by gcc3.4. (Mingw32)
in "gccfile.dat", I saved a seriers of data, including int and float
type, using
gf = fopen("gccfile.dat", "w");
fwrite(NLAM, sizeof(int),1, gf);
//repeat this sentence to store several vars,
NLAM,R,D,H,ALAM0,ALAM1,DLAM , with different type.
Now, I want to read datas in "gccfile.dat", and I have tried many
methods.
Way 1:
openr, lun, "gccfile.dat", /GET_LUN
readu,lun,NLAM,R,D,H,ALAM0,ALAM1,DLAM
print, NLAM,R,D,H,ALAM0,ALAM1,DLAM
It prints strange data like 3.36641e+038, and prompts:
% Program caused arithmetic error: Floating underflow
% Program caused arithmetic error: Floating illegal operand
Way 2: (learn from this forum. THANKS :) )
openr, lun, "gccfile.dat", /GET_LUN, /SWAP_ENDIAN
readu,lun,NLAM,R,D,H,ALAM0,ALAM1,DLAM
print, NLAM,R,D,H,ALAM0,ALAM1,DLAM
It still prints the garbage!
I have tested the endian-ness things with (from Paul. Thanks):
openr,lun,'shepp.sgm', /GET_LUN ; "shepp.sgm" is my file.
; -- Check the record size
RecordSize = 10000L * 4L
RecordSize_Test = 0L
READU, lun, RecordSize_Test
IF ( RecordSize_Test NE RecordSize ) THEN $
Swap = 1 $
ELSE $
Swap = 0
; -- Close the file
FREE_LUN, lun
print, "Swap", Swap
; The above Swap turns out 1. So swap is necessary.
Way 3:
openr, lun, "gccfile.dat", /GET_LUN ; Without /SWAP_ENDIAN
readu,lun,NLAM,R,D,H,ALAM0,ALAM1,DLAM
NLAM = SWAP_ENDIAN(NLAM)
print, NLAM,R,D,H,ALAM0,ALAM1,DLAM
Amazingly, NLAM (integer) is wrong, and other vars (float) are right!
I am totally confused by its behavious!
Additionally, I have tried another ways, and did't take effect.
byteorder, NLAM,R,D,H,ALAM0,ALAM1,DLAM, /lswap
One suggested "binread" function, but it doesn't exist in IDL6.0.
Thanks,
Tony
On 8 7 , 8 39 , Paul van Delst <Paul.vanDe...@noaa.gov> wrote:
> Nianming Zuo wrote:
>> Dear all,
>
>> I have sufferred file read/write problems between Fortran 90/95 and
>> IDL 6.0.
>
>> My Fortran compiler:
>> Silverfrost ftn95, Compatable for Fortran 77/90/95
>> http://www.silverfrost.com/12/ftn95/ftn95_feature_details.as p
>
>> IDL 6.0 (Interactive Data Language, RSI)
>
>> Both are in MS Windows XP(sp2) OS system.
>
>> Write data to a file by use of Fortran:
>> dimension dat(m, n)
>> !........ Manipulations..., matrix dat(m, n) is float
>> open(unit=11, file="file.dat", form="unformatted")
>> write(11) dat
>> !..........
>> ! The above are really f77 code, so I guess it is related to Compiler.
>
>> Read the data above by IDL6.0: (Way 1)
>> dat = fltarr(m,n)
>> openr, 1, 'file.dat'
>> readu, 1, b, dat, b
>
>> In "readu, 1, b, dat, b", the "b"s are used to skip the record area in
>> Fortran data format.
>> Unfortunately, it can not get the right result, and prompts "End of
>> the file"
>
>> I have also tried another way in IDL: (Way 2)
>> dat = fltarr(m,n)
>> openr, 1, 'file.dat' /f77_unformatted
>> readu, 1, dat
>
>> But, it prompts,
>> "% READU: Corrupted f77 unformatted file detected. "
>
>> For the above Fortran code, when it is compied by g77, IDL can read it
>> by Way 2.
>
>> So, I doubt that different compilers give different response to the
>> standard Fortran sentences ?
>> Since there is no f90_unformatted or f95_unformatted, f77/f90/f95 will
>> produce the same record for the "open-write" sentence.
>
>> Now, how can I read ftn95 compiled output data by IDL6.0 ? I have
>> searched this forum, but without any desirable results.
>
> Have a lookee at:
>
> http://groups.google.com/group/comp.lang.idl-pvwave/browse_t hread/thr...
>
> (Crikey that's a long link)
>
> cheers,
>
> paulv- -
>
> - -
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