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c fortran

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March 27, 2026 Score: 1 Rep: 40,671 Quality: Medium Completeness: 80%

You should provide Minimal Complete Verifiable Example, so your intent is clear and it is easier to provide a nice answer.

Anyway here I proposal of my own MCVE where it just works:

Fortran side code:

module mymodule
  use isocbinding
  implicit none
  type, bind(c) :: coordinatesfloat
    real(cfloat) :: x
    real(cfloat) :: y
  end type coordinatesfloat
contains
  subroutine processcoords(coords) bind(c, name="processcoords")
    type(coordinatesfloat), intent(inout) :: coords
    coords%x = coords%x * 2.0
    coords%y = coords%y * 2.0
  end subroutine
end module mymodule

C++ side code:

#include 
// Matches the Fortran bind(c) type exactly
struct coordinatesfloat {
    float x;
    float y;
};
// Declare the Fortran function with C linkage
extern "C" {
    void process_coords(coordinatesfloat* coords);
}
int main() {
    coordinatesfloat c = {3.0f, 4.0f};
    std::cout
March 27, 2026 Score: 0 Rep: 18,163 Quality: Low Completeness: 0%

It looks fine, although OP wants to use it in C.

March 27, 2026 Score: 0 Rep: 40,671 Quality: Low Completeness: 20%

Here C++ is used just to print some data. Everything else is C or Fortran. https://godbolt.org/z/qxTjMG8Gh