NetCDF-3 classic and 64-bit offset files support 6 atomic data types, and none of the user defined datatype introduced in NetCDF-4.
The following table gives the netCDF-3 external data types and the corresponding type constants for defining variables in the C interface:
| Type | C #define | Bits
|
| byte | NC_BYTE | 8
|
| char | NC_CHAR | 8
|
| short | NC_SHORT | 16
|
| int | NC_INT | 32
|
| float | NC_FLOAT | 32
|
| double | NC_DOUBLE | 64
|
The first column gives the netCDF external data type, which is the same as the CDL data type. The next column gives the corresponding C pre-processor macro for use in netCDF functions (the pre-processor macros are defined in the netCDF C header-file netcdf.h). The last column gives the number of bits used in the external representation of values of the corresponding type.