**petsc-master 2020-01-15**

# PetscDataType

Used for handling different basic data types.
### Synopsis

typedef enum {PETSC_DATATYPE_UNKNOWN = 0,
PETSC_DOUBLE = 1, PETSC_COMPLEX = 2, PETSC_LONG = 3, PETSC_SHORT = 4, PETSC_FLOAT = 5,
PETSC_CHAR = 6, PETSC_BIT_LOGICAL = 7, PETSC_ENUM = 8, PETSC_BOOL = 9, PETSC___FLOAT128 = 10,
PETSC_OBJECT = 11, PETSC_FUNCTION = 12, PETSC_STRING = 13, PETSC___FP16 = 14, PETSC_STRUCT = 15,
PETSC_INT = 16, PETSC_INT64 = 17} PetscDataType;

### Notes

Use of this should be avoided if one can directly use MPI_Datatype instead.
PETSC_INT is the datatype for a PetscInt, regardless of whether it is 4 or 8 bytes.
PETSC_REAL, PETSC_COMPLEX and PETSC_SCALAR are the datatypes for PetscReal, PetscComplex and PetscScalar, regardless of their sizes.

### Developer comment

It would be nice if we could always just use MPI Datatypes, why can we not?
If you change any values in PetscDatatype make sure you update their usage in
share/petsc/matlab/PetscBagRead.m

TODO: Add PETSC_INT32 and remove use of improper PETSC_ENUM

### See Also

PetscBinaryRead(), PetscBinaryWrite(), PetscDataTypeToMPIDataType(),

PetscDataTypeGetSize()

### Level

beginner

### Location

include/petscsystypes.h
### Examples

src/sys/examples/tutorials/ex5.c.html

src/vec/vec/examples/tutorials/ex6.c.html

src/vec/vec/examples/tutorials/ex6f.F90.html

src/dm/examples/tutorials/ex20.c.html

src/dm/examples/tutorials/swarm_ex3.c.html

Index of all Sys routines

Table of Contents for all manual pages

Index of all manual pages