:orphan:
# DMCompareLabels
Compare labels of two `DMPLEX` meshes 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMCompareLabels(DM dm0, DM dm1, PetscBool *equal, char **message)
```
Collective; No Fortran Support


## Input Parameters

- ***dm0 -*** First `DM` object
- ***dm1 -*** Second `DM` object


Output Parameters

- ***equal   -*** (Optional) Flag whether labels of dm0 and dm1 are the same
- ***message -*** (Optional) Message describing the difference, or `NULL` if there is no difference





## Notes
The output flag equal will be the same on all processes.

If equal is passed as `NULL` and difference is found, an error is thrown on all processes.

Make sure to pass equal is `NULL` on all processes or none of them.

The output message is set independently on each rank.

message must be freed with `PetscFree()`

If message is passed as `NULL` and a difference is found, the difference description is printed to stderr in synchronized manner.

Make sure to pass message as `NULL` on all processes or no processes.

Labels are matched by name. If the number of labels and their names are equal,
`DMLabelCompare()` is used to compare each pair of labels with the same name.


## See Also
 [](ch_dmbase), `DM`, `DMLabel`, `DMAddLabel()`, `DMCopyLabelsMode`, `DMLabelCompare()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/interface/dm.c.html#DMCompareLabels">src/dm/interface/dm.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/label/tutorials/ex1.c.html">src/dm/label/tutorials/ex1.c</A><BR>


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[Index of all DM routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)