# PetscViewerReadable
Return a flag whether the viewer can be read from 
## Synopsis
```
#include "petscviewer.h" 
PetscErrorCode PetscViewerReadable(PetscViewer viewer, PetscBool *flg)
```
Not Collective


## Input Parameters

- ***viewer -*** the `PetscViewer` context



## Output Parameters

- ***flg -*** `PETSC_TRUE` if the viewer is readable, `PETSC_FALSE` otherwise



## Note
`PETSC_TRUE` means that viewer's `PetscViewerType` supports reading (this holds e.g. for `PETSCVIEWERBINARY`)
and viewer is in a mode allowing reading, i.e. `PetscViewerFileGetMode()`
returns one of `FILE_MODE_READ`, `FILE_MODE_UPDATE`, `FILE_MODE_APPEND_UPDATE`.




## See Also
 [](sec_viewers), `PetscViewer`, `PetscViewerWritable()`, `PetscViewerCheckReadable()`, `PetscViewerCreate()`, `PetscViewerFileSetMode()`, `PetscViewerFileSetType()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/classes/viewer/interface/view.c.html#PetscViewerReadable">src/sys/classes/viewer/interface/view.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/sys/classes/viewer/interface/view.c)


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