There's an example C program
here. Also, part of the shipping documentation is an app note titled "LabVIEW Data Storage Formats" that you need to understand when you write your LabVIEW program to save binary data and when you write the Fortran/C program to read it.
And just to satisfy my curiosity, why do you want to use Fortran/C for post-processing instead of LabVIEW?