# PetscInfoActivateClass
Activates `PetscInfo()` messages for a PETSc object class. 
## Synopsis
```
#include "petscsys.h"   
PetscErrorCode PetscInfoActivateClass(PetscClassId classid)
```
Not Collective


## Input Parameter

- ***classid -*** The object class, e.g., `MAT_CLASSID`, `SNES_CLASSID`, etc.



## Note
One can pass 0 to activate all messages that are not associated with an object.




## See Also
 `PetscInfoDeactivateClass()`, `PetscInfo()`, `PetscInfoAllow()`, `PetscInfoSetFromOptions()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/info/verboseinfo.c.html#PetscInfoActivateClass">src/sys/info/verboseinfo.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex7.c.html">src/mat/tutorials/ex7.c.html</A><BR>


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


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