Do you know of any resources to brush up on the pointer aspect of swift ?
*___________________________________* *James⎥Head of Trolls* *ja...@supmenow.com <ja...@supmenow.com>⎥supmenow.com <http://supmenow.com>* *Sup* *Runway East * *10 Finsbury Square* *London* * EC2A 1AF * On 29 July 2016 at 09:10, Dmitri Gribenko <griboz...@gmail.com> wrote: > On Fri, Jul 29, 2016 at 12:55 AM, James Campbell <ja...@supmenow.com> > wrote: > > So this: > > > > if let data = someArrayGeneratingFunction() { > > cFunction(UnsafeMutablePointer(data)) > > } > > > > Has issues with the array passed to c getting corrupted, but this > doesn't: > > > > let data = someArrayGeneratingFunction() > > > > if let data = data { > > cFunction(UnsafeMutablePointer(data)) > > } > > Neither piece of code is guaranteed to work. (You are just getting > lucky that the second one happens to work.) Array-to-pointer > conversion only extends the lifetime of the array until the immediate > function call returns. So after UnsafeMutablePointer(data) returns, > the array can be freed. > > Use someArrayGeneratingFunction.withUnsafeMutableBuffer { ... } instead. > > Dmitri > > -- > main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if > (j){printf("%d\n",i);}}} /*Dmitri Gribenko <griboz...@gmail.com>*/ >
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