[petsc-users] How to use PetscViewerVTKGetDM

[Lawrence Mitchell]

> On 2 Nov 2018, at 14:58, 陳宗興 via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Hi,
> 
> I have created a DMPlex using DMPlexCreateFromFile,
> and I use PetscObjectSetName to create the name of DM.
> I have occurred some problem when I try to use PetscViewerVTKGetDM.
> This is what I write:
> 
>      DM   dm;
>      ...
>      PetscObjectSetName((PetscObject) dm, "Mesh");
>      ...
>      PetscViewerVTKGetDM(viewer, (PetscObject) dm);
> 
> And here is the output of waring:
>      warning: passing argument 2 of ‘PetscViewerVTKGetDM’ from incompatible pointer type [-Wincompatible-pointer-types]
>      ierr = PetscViewerVTKGetDM(viewer, (PetscObject) dm);CHKERRQ(ierr);
>                                                                   ^
>      note: expected ‘struct _p_PetscObject **’ but argument is of type ‘struct _p_PetscObject *'
>      PETSC_EXTERN PetscErrorCode PetscViewerVTKGetDM(PetscViewer,PetscObject*);
>                                                              ^~~~~~~~~~~~~~~~~~~

You need to pass a pointer to the PetscObject:

PetscViewerVTKGetDM(viewer, (PetscObject *)&dm);

Cheers,

Lawrence