# PetscObjectComm
Gets the MPI communicator for any `PetscObject` regardless of the type. 
## Synopsis
```
#include "petscsys.h"    
MPI_Comm PetscObjectComm(PetscObject obj)
```
Not Collective


## Input Parameter

- ***obj -*** any PETSc object, for example a `Vec`, `Mat` or `KSP`. Thus must be
cast with a (`PetscObject`), for example,
`PetscObjectComm`((`PetscObjec`t)mat,...);



## Output Parameter

- ***comm -*** the MPI communicator or `MPI_COMM_NULL` if object is not valid





## See Also
 `PetscObject`, `PetscObjectGetComm()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/objects/gcomm.c.html#PetscObjectComm">src/sys/objects/gcomm.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/tutorials/ex1.c.html">src/vec/vec/utils/tagger/tutorials/ex1.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/sf/tutorials/ex1.c.html">src/vec/is/sf/tutorials/ex1.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex8.c.html">src/mat/tutorials/ex8.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/tutorials/ex10.c.html">src/dm/impls/plex/tutorials/ex10.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/tutorials/ex11.c.html">src/dm/impls/plex/tutorials/ex11.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/tutorials/ex6.c.html">src/dm/impls/plex/tutorials/ex6.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/tutorials/ex7.c.html">src/dm/impls/plex/tutorials/ex7.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex2.c.html">src/dm/impls/stag/tutorials/ex2.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex3.c.html">src/dm/impls/stag/tutorials/ex3.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex4.c.html">src/dm/impls/stag/tutorials/ex4.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex6.c.html">src/dm/impls/stag/tutorials/ex6.c.html</A><BR>


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/objects/gcomm.c)


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