[racket] FFI Pointer to Pointer

From: Freezerburn (vince.raiken at gmail.com)
Date: Sun Jun 10 09:04:38 EDT 2012

I think I might have been unclear about what I was asking. If we assume I have that same code you just posted, how would I go about using it through the Racket FFI? I know I can define a _my_c_struct-pointer, but how do I make a pointer to that pointer to pass to the C function?

On Jun 10, 2012, at 5:42 AM, Joshua Ewulo <jewulo at gmail.com> wrote:

> Say you have a struct.
> struct my_c_struct {};
> my_c_struct *ptr = 0; // uninitialised pointer
> You need to prototype the function with a pointer to a pointer
> void my_func(my_c_struct **pptr);
> void my_func(my_c_struct **pptr)
> {
>     *ptr = new my_c_struct;
>     if (!*ptr) printf ("error no memory\n");
>     else printf ("aye memory\n");
> }
> On 10 June 2012 01:57, Vince Kuyatt <vince.raiken at gmail.com> wrote:
> I need to be able to define a variable which is an un-initialized pointer to a C struct, then pass a reference to that pointer to a C function. How would I go about doing this? 
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