petsc-3.10.5 2019-03-28
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# PetscBinaryWrite

Writes to a binary file.

### Synopsis

    PetscErrorCode  PetscBinaryWrite(int fd,void *p,PetscInt n,PetscDataType type,PetscBool  istemp)

Not Collective

### Input Parameters

| fd | - the file
| p | - the buffer
| n | - the number of items to write
| type | - the type of items to read (PETSC_INT, PETSC_DOUBLE or PETSC_SCALAR)
| istemp | - PETSC_FALSE if buffer data should be preserved, PETSC_TRUE otherwise.

### Notes

PetscBinaryWrite() uses byte swapping to work on all machines; the files are written using big-endian ordering to the file. On small-endian machines the numbers are converted to the big-endian format when they are written to disk. When PETSc is ./configure with --with-64bit-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-64bit-indices is used.

If running with __float128 precision the output is in __float128 unless one uses the -binary_write_double option

The Buffer p should be read-write buffer, and not static data. This way, byte-swapping is done in-place, and then the buffer is written to the file.

This routine restores the original contents of the buffer, after it is written to the file. This is done by byte-swapping in-place the second time. If the flag istemp is set to PETSC_TRUE, the second byte-swapping operation is not done, thus saving some computation, but the buffer is left corrupted.

Because byte-swapping may be done on the values in data it cannot be declared const

### See Also

PetscBinaryRead(), PetscBinaryOpen(), PetscBinaryClose(), PetscViewerBinaryGetDescriptor(), PetscBinarySynchronizedWrite(),
PetscBinarySynchronizedRead(), PetscBinarySynchronizedSeek()

### Level

advanced

### Location

src/sys/fileio/sysio.c

### Examples

src/vec/vec/examples/tutorials/ex6.c.html
Index of all Sys routines
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Index of all manual pages