Variables can be made accessible from C using the C binding attribute, optionally together with specifying a binding name. Those variables have to be declared in the declaration part of a MODULE
, be of interoperable type, and have neither the pointer
nor the allocatable
attribute.
MODULE m USE myType_module USE ISO_C_BINDING integer(C_INT), bind(C, name="_MyProject_flags") :: global_flag type(myType), bind(C) :: tp END MODULE
Here, _MyProject_flags
is the case-sensitive name of the variable as seen from C programs while global_flag
is the case-insensitive name as seen from Fortran. If no binding name is specified, as for tp, the C binding name is the (lowercase) Fortran binding name. If a binding name is specified, only a single variable may be after the double colon. Note of warning: You cannot use a global variable to access errno of the C library as the C standard allows it to be a macro. Use the IERRNO
intrinsic (GNU extension) instead.
© Free Software Foundation
Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gfortran/Interoperable-Global-Variables.html