# PetscHelpPrintf
Prints help messages. 
## Synopsis
```
#include <petscsys.h>
PetscErrorCode (*PetscHelpPrintf)(MPI_Comm comm, const char format[],args);
```
Collective on comm


## Input Parameters

- ***comm -*** the MPI communicator over which the help message is printed
- ***format -*** the usual printf() format string
- ***args -*** arguments to be printed





## Fortran Note
This routine is not supported in Fortran.


## Note
You can change how help messages are printed by replacing the function pointer with a function that does not simply write to stdout.

To use, write your own function, for example,
```none
PetscErrorCode mypetschelpprintf(MPI_Comm comm,const char format[],....)
```
```none
{$ PetscFunctionReturn(0);
```
```none
}then do the assignment
```
```none
PetscHelpPrintf = mypetschelpprintf;
```
You can do the assignment before `PetscInitialize()`.

The default routine used is called `PetscHelpPrintfDefault()`.


## See Also
 `PetscFPrintf()`, `PetscSynchronizedPrintf()`, `PetscErrorPrintf()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscsys.h.html#PetscHelpPrintf">include/petscsys.h</A>


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