>
>I know that passing characters to f77 routines is tricky, but I hope that
someone has done this before:
>
>I want to fill an array of strings in the f77 routine - how do I handle that?
For example, this might make sense but it does not work:
>
>-------------
>external MYMOD "./my_mod.f"
>
>begin
>
>char_array = new((/1000,14/),char)
>
>MYMOD::my_mod(char_array)
>
>end
>
>--------------
>C NCLFORTSTART
>subroutine my_mod(ch_array)
>
>character*14 ch_array(1000)
>
>C NCLEND
>
>C fill the array
>
>end
>
>Ideas? I am using version 4.2.0.a030 with Debian Linux.
>
Hi Josh,
Some general comments ... then a non-elegant 'work around'!
[0] I don't think this is a system issue. It is a fortran/C
language issue. I speculate that the fortran standard
does not specify how to pass fortran character variables.
I think it is left to each compiler how they can most efficiently
implement this. Also, fortran has no concept of "strings"
even though they 'look' like NCL strings.
For fortran, I'll use f77 since that is what you are using
[1] You can pass an NCL string to fortran
NCL: s = "Sample"
mymod:foo1(...,s,...)
f77: subroutine foo1 (...,sc,...)
character*(*) sc ! note syntax
print *, sc ! works fine
[2] You can pass a fortran character variable to NCL but
(a) user must allocate a character variable in NCL script
(a) then the user must convert it to a string.
f77: subroutine foo2 (...,fchar,...)
character*7 fchar
fchar = "orange"
NCL: char = new ( 7, "character") ; will be returned to NCL script
mymod:foo2(...,char,...) ; invoke shared object
str = chartostring(char) ; convert to string
[3] of course, you can pass multiple arguments
---
sc1 = "..."
sc2 = "..."
:
scn = "..."
subroutine foo3(...,sc1,sc2,...,scn,...) ; ncl=>fortran
---
char1 = new ( 7, "character")
char2 = new ( 9, "character")
charn = new (12, "character")
mymod::foo4(...,char1,char2,charn,....)
str1 = chartostring(char1)
str2 = chartostring(char2)
strn = chartostring(charn)
[4] A non-elegant work around for character variables in fortran
being passed back to NCL
f77: The following is in file my_mod.f
C NCLFORTSTART
subroutine josh(...,fname,...)
character*(*) fname
character*14 char_array(1000)
C NCLEND
open(11,file=fname) ! default is ascii, sequential
do n=1,1000
write(10,*) char_array(n)
end do
close (11)
return
end
NCL: external MYMOD "./my_mod.so"
fname = "whatever"
MYMOD::josh(...,fname,...)
fStrings = asciiread (fname, -1, "string")
nStrings = dimsizes(fStrings)
; if u no longer need the ascii file
system("/bin/rm "+fname) ; delete temporary file
[5] NCL strings [is this not what u really mean] passed to
f77 code. It is basically the reverse of [4]
NCL: sString = new ( 1000, "string")
: ; fill strings
fname = "WhatEver"
asciiwrite (fname, sString)
system("/bin/rm "+fname)
f77:
C NCLFORTSTART
subroutine josh(...,fname,...)
character*(*) fname
character*14 chrstr(1000)
C NCLEND
open (11,file=fname)
do n=1,1000
read(11,"(a)") chrstr(n)
end do
HTH
D
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