Re: Interfacing with C

[Simon Wright <simon@pogner.demon.co.uk>]

Jan Kroken <jankr@nntp.ifi.uio.no> writes:

> void y (datum d)
> {
> 	printf("d.size=%d\n",d.dsize);
> }

> procedure y (d: datum);
> pragma Import(C,y,"y");

> What I don't understand here is that x works perfectly, while
> the datum in y gets fucket up. Why?

Normally when passing a struct in C you would pass a pointer to it:

  void y (datum *d)

I don't know what the standard says about passing structs, but it's
quite likely your Ada and C compilers are disagreeing.

See LRM B.3(69): An Ada parameter of a record type T, of any mode, is
passed as a t* argument to a C function, where t is the C struct
corresponding to the Ada type T.