On 2013-12-01 04:46, Craig Dillabaugh wrote:
Since questions about calling C from D seem to be popular today, I thought I would throw this one out there.I am trying to call a C function which takes as parameters several arrays of doubles. It is valid to have some arrays passed a NULL pointers in the C code. To call this from D I've come up with the following, but it seems like a bit of a hack. double[] x1 = [ 2.4, 3.7, 9.7, 4.5 ]; double[] y1 = [ 2.4, 9.8, 9.1, 3.4 ]; double[] empty; SHPObject*[] shape_ptrs; shape_ptrs ~= SHPCreateSimpleObject( SHPT_POLYGON, to!int(x1.length), x1.ptr, y1.ptr, empty.ptr ); It should be clear what is going on. A POLYGON is defined as a set of points (provided as arrays of doubles), with X,Y and optional Z coordinates. In this case I want a 2D polygon, so I want the final Z array to be empty. I wanted to just write 0 as the final parameter, but that didn't work, so I tried to!(double*)(0), and that didn't make the compiler happy either. I guess using the empty.ptr bit makes sense, in that the final array is meant to be empty, so pass it a pointer to an empty array. But it seems a bit hackish that I need to declare an additional empty array just to call this function. Is there an accepted 'proper' way of passing NULL pointers to C functions from D?
Well, there is null. -- Simen
