Using and Porting GNU Fortran
12.1.2 Accessing Type Information in C
Generally, C code written to link with
g77 code--calling and/or being
called from Fortran--should `#include <g2c.h>' to define the C
versions of the Fortran types.
Don't assume Fortran INTEGER types
correspond to C ints, for instance; instead, declare them as
integer, a type defined by `g2c.h'.
`g2c.h' is installed where gcc will find it by
default, assuming you use a copy of gcc compatible with
g77, probably built at the same time as g77.
