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# PetscBinarySynchronizedRead
Reads from a binary file, all MPI processes get the same values 
## Synopsis
```
PetscErrorCode PetscBinarySynchronizedRead(MPI_Comm comm, int fd, void *data, PetscInt num, PetscInt *count, PetscDataType type)
```
Collective


## Input Parameters

- ***comm -*** the MPI communicator
- ***fd -*** the file descriptor
- ***num  -*** the maximum number of items to read
- ***type -*** the type of items to read (`PETSC_INT`, `PETSC_REAL`, `PETSC_SCALAR`, etc.)



## Output Parameters

- ***data -*** the buffer, an array of the type that matches the value in `type`
- ***count -*** the number of items read, optional





## Notes
Does a `PetscBinaryRead()` followed by an `MPI_Bcast()`

If `count` is not provided and the number of items read is less than
the maximum number of items to read, then this routine errors.

`PetscBinarySynchronizedRead()` uses byte swapping to work on all machines.
The files  are written using big-endian ordering to the file. On little-endian machines the numbers
are converted to the big-endian format when they are written to disk.
When PETSc is configured using `./configure with --with-64-bit-indices` the integers are written to the
file as 64-bit integers, this means they can only be read back in when the option `--with-64-bit-indices`
is used.


## See Also
 `PetscBinaryWrite()`, `PetscBinaryOpen()`, `PetscBinaryClose()`, `PetscBinaryRead()`, `PetscBinarySynchronizedWrite()`,
`PetscBinarySynchronizedSeek()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/sys/fileio/sysio.c.html#PetscBinarySynchronizedRead">src/sys/fileio/sysio.c</A>


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


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