• Well-documented: The netCDF Fortran-90 Users Guide is complete and up-to-date.
• Overloaded functions and optional arguments: The Fortran-90 interface is significantly simpler than either the C or Fortran-77 interfaces because of its use of overloaded functions and optional arguments. For example one nf90_put_var() function replaces 30 nf_put_var() functions in the Fortran-77 interface and 40 nc_put_var() functions in the C interface.
• Fewer arguments to functions: string lengths need not be passed for attribute strings, and array lengths need not be passed for dimension arrays. There are fewer and simpler inquiry functions in the Fortran-90 interface with the use of optional arguments.
• Improved error checking: use of intent declarations lets compilers check whether some arguments are used correctly.
• Arbitrary array sections supported: The language allows arbitrary array sections to be passed to any procedure, which may simplify programming.
• Full (but not portable) support for netCDF-4 extensions.

• Order of subscripts in CDL: CDL uses row-major order for matrices (last dimension varies fastest), but Fortran uses column-major order (first dimension varies fastest), which can occasionally lead to confusion.
• Not well-tested: Only a few simple tests are run when the netCDF Fortran-90 library is installed.
• No ncgen support: ncgen cannot generate Fortran-90 code, although the Fortran-77 code it generates works from Fortran-90.
• Memory handling: You have to provide memory space for any netCDF data values and attribute values you read.
• Error handling: The status of every function call must be checked, which detracts from code clarity.

• Implemented as a thin layer on top of the Fortran-77 library, which in turn is a thin layer on top of the C netCDF-3 library.

Annotated examples of complete Fortran90 netCDF programs are available from the program examples page.

2009 Unidata NetCDF Workshop for Developers and Data Providers > NetCDF APIs