Bidimensional dynamic array problem
Frits van Bommel
fvbommel at REMwOVExCAPSs.nl
Tue Mar 6 07:50:13 PST 2007
orgoton wrote:
> I have this
>
> struct Vertex{
> (...)
> float z;
> }
>
> then:
> Vertex vData[][];
>
> Somewhere later:
> vData.length=sizeX;
> foreach(Vertex strip[]; vData[]) strip.length=sizeY;
foreach(inout Vertex[] strip; vData) strip.length = sizeY;
or just:
foreach(inout strip; vData) strip.length = sizeY;
Note: only the inout is significant, the rest is just nitpicking :P.
If you don't specify 'inout', you're just modifying a local copy of the
element...
And IIRC something like "vData = new Vertex[][](sizeX, sizeY)" should
replace that entire code sequence, initializing the outer array to an
array of sizeX arrays of length sizeY.
> Here the array is initialized. So far, I think I haven't done anything illegal. (SizeX and SizeY are runtime values, ushort vars). So first I say how many strips I want, and next, I put in how many elements that strip will have.
You haven't done anything illegal, just something wrong ;).
You haven't initialized the array the way you thought you did: it's just
an array of _empty_ dynamic arrays at this point.
> ulong m;
> foreach (Vertex[] strip; vData)
(this loop doesn't require 'inout' since the array itself isn't
modified, just the data it references)
> {
> foreach (Vertex vertex; strip)
foreach(inout Vertex vertex; strip)
(or: foreach(inout vertex; strip))
> {
> file.read(vertex.height);
> m++;
> }
> }
>
> Here I read the values from a file. First, I select a strip, and then go through all the elements of that array and read their values. "m" is a counter to see how many elements where read.
>
> The thing is, m=0 at the end of the loop. What did I do wrong?
Since you didn't initialize the elements of vData, their lengths are all
still zero. So your inner loop is never executed.
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