# PetscOptionsLeft
Prints to screen any options that were set and never used. 
## Synopsis
```
#include "petscsys.h"   
PetscErrorCode PetscOptionsLeft(PetscOptions options)
```
Not Collective


## Input Parameter

- ***options -*** options database; use NULL for default global database



## Options Database Key

- ***-options_left -*** activates `PetscOptionsAllUsed()` within `PetscFinalize()`



## Notes
This is rarely used directly, it is called by `PetscFinalize()` in debug more or if -options_left
is passed otherwise to help users determine possible mistakes in their usage of options. This
only prints values on process zero of `PETSC_COMM_WORLD`.

Other processes depending the objects
used may have different options that are left unused.




## See Also
 `PetscOptionsAllUsed()`

## Level
advanced

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


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


[Index of all Sys routines](index.md)  
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