Sounds good, writing it up now. One thing:
Would it also work if instead of instead of declaring a 1-element array with Cint[0], you just declared an actual Cint with convert(Cint, 0) (or some other mechanism for creating an int)? Or would that not be the same thing because Cint is supposed to be immutable? -s On Sat, Dec 21, 2013 at 3:21 PM, Tim Holy <[email protected]> wrote: > On Saturday, December 21, 2013 02:28:01 PM Spencer Russell wrote: > > Ah, thanks for this! Just yesterday I was trying to figure out how to > pass > > some pointers so they could be modified by a C function. This is a pretty > > common idiom in lots of C code, maybe this little trick could be added to > > the docs on C interop? > > Pull requests are always welcome, and there are advantages to having people > with "fresh eyes" contributing to the documentation. > > For documentation, you don't even need to mess with git; you can edit > right on > the webpage. > > Best, > --Tim > > > > > -s > > > > On Sat, Dec 21, 2013 at 10:31 AM, Isaiah Norton > <[email protected]>wrote: > > > ``` > > > > > > width = Cint[0] > > > > > > range = Cfloat[0] > > > > > > ccall(:foo, Void, (Ptr{Cint}, Ptr{Cfloat}), width, range) > > > > > > ``` > > > > > > > > > Explanation: > > > > > > - the first line declares an array with a single element of Cint > (Int32) > > > type > > > > > > - ccall automatically passes the address of the first (here, only) > element > > > of the array when you request Ptr{Cint} / Ptr{Cfloat} in the type > > > specification tuple> > > > On Sat, Dec 21, 2013 at 10:15 AM, Andreas Lobinger > <[email protected]>wrote: > > >> Hello, > > >> > > >> i'm trying to use an external library for certain things and i need > > >> somehow a 1:1 relation to certain input/output parameters: > > >> > > >> *float > > >> *int > > >> > > >> I'm aware that the most promising thing is to do a type definition. > > >> > > >> Is > > >> > > >> type myiothing > > >> > > >> input::Array{Float32,1} > > >> output::Array{Int32,1} > > >> n_points:Int32 > > >> > > >> end > > >> > > >> the way to go, or is there something i'm missing (i have no clear > > >> understanding, what Array{something,1} is creating only a pointer)? > > >> > > >> Wishing a happy day, > > >> > > >> Andreas >
