如何在不将指针作为参数传递的情况下，将一个 .c 文件中定义的结构填充到另一个 .c 中定义的函数中？

Question

I have a C function (store_mode_ - defined in file_A.c) which is called in a Fortran code.

It looks like this..

// Create a global structure to populate with current mode frequencies
struct minos_modes current_modes;
static int nmode = 0;

void
store_mode_( int *n, int *l, double *w, double *U )
{
  if ( nmode == MODE_MAX )
    {
      printf( "[ store_mode_ ] Error: MODE_MAX is too small\n" );
      exit( 1 );
    }
  current_modes.mode_n[nmode] = *n;
  current_modes.mode_l[nmode] = *l;
  current_modes.mode_w[nmode] = *w;
  current_modes.mode_U[nmode] = *U;
  nmode += 1;
  current_modes.len = nmode;
}

I am trying to fill a structure with the values (n, l, w, U) passed as arguments in the Fortran call. The above code works when defined immediately above my main in File_B.c, which calls the fortran code within it.

However.. If I define the above function in file_A.c (the one that main isn't in) it doesn't work. I appreciate this is due to the lack of shared globals between .c files. I was wondering if there is a solution for this? Perhaps with extern, though I played a little with no success.

Answer 1

static int nmode = 0;

If you are including that line in both files, then you have two nmode variables, one in each file. The static makes the symbol private to the translation unit .

Instead, you probably want

int nmode;

in one file, and

extern int nmode;

in the other. (There's no need to initialize it to zero explicitly. That's guaranteed for static storage.)