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DllImport with int*
f#

Now I have to solve DllImport with int*

I have
[<DllImport(@"netcdf.dll",EntryPoint="nc_inq_vardimid")>]
extern int nc_inq_vardimid_(int ncid, int varid, int *dimidsp)

or equivalent (?)
[<DllImport(@"netcdf.dll",EntryPoint="nc_inq_vardimid")>]
extern int nc_inq_vardimid_(int ncid, int varid, int dimidsp[])

I write F# function:

let Inq_vardimid ncid varid =
let mutable thisncid = ncid
let mutable thisvarid = varid
let mutable dimidsp = [| 0;0;0 |]
let status = nc_inq_vardimid_(thisncid,thisvarid,&&dimidsp)
^^^^^^^error
dimidsp, status

I get error
c:\at_work\fsharp\netcdf\netcdf_small.fs(136,58): error FS0001: This expression has type
int array
but is here used with type
int

c:\at_work\fsharp\netcdf\netcdf_small.fs(136,56): error FS0191: Invalid mutation of a constant expression. Consider copying the expression to a mutable local, e.g. 'let mutable x = ...'.

stopped due to error

Sincerely, I have no idea what is the problem.
Do you have hint? suggestion? exact declaration?

.

Ok.

I declare:
[<DllImport(@"netcdf.dll",EntryPoint="nc_inq_vardimid")>]
extern int nc_inq_vardimid_(int ncid, int varid, int[] dimidsp)

and create function
let Inq_vardimid ncid varid =
let mutable thisncid = ncid
let mutable thisvarid = varid
let mutable (dimidsp: int[]) = Array.zero_create 3
let status = nc_inq_vardimid_(thisncid,thisvarid,dimidsp)
dimidsp, status

My inspiration is Expert F#, section Function Pointers (page 516)
example with transformArray with argument int[] data

By on 6/8/2008 7:30 PM ()

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