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October 08, 2012 Growing multidimensional dynamic arrays | ||||
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Hi all, This seems like something that should be possible: how do I grow multidimensional arrays? I want something like this: struct X{ ... }; X*[][] listOfLists; foreach ( x ; otherListOfX ) { if ( newListForArbitraryReason ) { listOfLists ~= new X*[]; } listOfLists[$] ~= x; } Now, this doesn't compile, because I _have_ to give a size to new X*[](arbitrary_number), and the listOfLists[$] ~= x; line never works (hangs at runtime). So, how would I go about doing this? My apologies if this is something really obvious. |
October 08, 2012 Re: Growing multidimensional dynamic arrays | ||||
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Posted in reply to KillerSponge | On 10/08/2012 06:12 AM, KillerSponge wrote: > Hi all, > > This seems like something that should be possible: how do I grow > multidimensional arrays? > > I want something like this: > > struct X{ ... }; > X*[][] listOfLists; > foreach ( x ; otherListOfX ) { > if ( newListForArbitraryReason ) { > listOfLists ~= new X*[]; > } > > listOfLists[$] ~= x; > } > > Now, this doesn't compile, because I _have_ to give a size to new > X*[](arbitrary_number), and the listOfLists[$] ~= x; line never works > (hangs at runtime). > > So, how would I go about doing this? My apologies if this is something > really obvious. I don't see the need for 'new' nor the use of a pointer, so I will not use them (yet): :) import std.stdio; struct X { int i; } void main() { X[][] listOfLists; auto otherListOfX = [ X(1), X(2), X(3) ]; auto newListForArbitraryReason = true; foreach (x; otherListOfX) { if (newListForArbitraryReason) { X[] newList = [ x ]; listOfLists ~= newList; } } writeln(listOfLists); } The body of foreach can be shorter: listOfLists ~= [ x ]; Also note that - There is no need for the semicolon at the end of the struct definition. - $ is not a valid index value. The last element is indexed by $-1. Ali -- D Programming Language Tutorial: http://ddili.org/ders/d.en/index.html |
October 08, 2012 Re: Growing multidimensional dynamic arrays | ||||
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Posted in reply to Ali Çehreli | On Monday, 8 October 2012 at 13:56:00 UTC, Ali Çehreli wrote:
> I don't see the need for 'new' nor the use of a pointer, so I will not use them (yet): :)
>
> import std.stdio;
>
> struct X
> {
> int i;
> }
>
> void main()
> {
> X[][] listOfLists;
>
> auto otherListOfX = [ X(1), X(2), X(3) ];
> auto newListForArbitraryReason = true;
>
> foreach (x; otherListOfX) {
> if (newListForArbitraryReason) {
> X[] newList = [ x ];
> listOfLists ~= newList;
> }
> }
>
> writeln(listOfLists);
> }
>
> The body of foreach can be shorter:
>
> listOfLists ~= [ x ];
>
> Also note that
>
> - There is no need for the semicolon at the end of the struct definition.
>
> - $ is not a valid index value. The last element is indexed by $-1.
>
> Ali
Ah, that works great (even with pointers ;)! Thanks a lot! :) It seems so obvious now.
And the use of $ was indeed a stupid mistake on my part. I guess I was confused because of the way it is often used in slicing. I really should pay attention to that :)
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