On 05/07/2015 07:39 PM, Dennis Ritchie wrote:
On Friday, 8 May 2015 at 02:23:23 UTC, E.S. Quinn wrote:
It's because arrays are references types, and .dup is a
strictly
shallow copy, so you're getting two outer arrays that
reference
the same set of inner arrays. You'll have to duplicated each
of
the inner arrays yourself if you need to make a deep copy.
Thank you. It really works :)
-----
import std.stdio;
void main() {
auto c = [[[1, 2, 3], [4, 5, 6, 7, 8]],
[[9, 10], [11, 12, 13]]];
auto d = [[c[0][0].dup, c[0][1].dup],
[c[1][0].dup, c[1][1].dup]];
d[0][1][1 .. $ - 1] *= 3;
writeln("c = ", c);
// [[[1, 2, 3], [4, 5, 6, 7, 8]],
// [[9, 10], [11, 12, 13]]] // OK
writeln("d = ", d);
// [[[1, 2, 3], [4, 15, 18, 21, 8]],
// [[9, 10], [11, 12, 13]]] // OK
}
-----
http://ideone.com/kJVUhd
Maybe there is a way to create .globalDup for multidimensional
arrays?
In D, everything is possible and very easy. :p I called it
deepDup:
import std.stdio;
import std.traits;
import std.range;
import std.algorithm;
auto deepDup(A)(A arr)
if (isArray!A)
{
static if (isArray!(ElementType!A)) {
return arr.map!(a => a.deepDup).array;
} else {
return arr.dup;
}
}
void main()
{
auto c = [[[1, 2, 3], [4, 5, 6, 7, 8]],
[[9, 10], [11, 12, 13]]];
auto d = c.deepDup;
d[0][1][1 .. $ - 1] *= 3;
writeln("c = ", c);
// [[[1, 2, 3], [4, 5, 6, 7, 8]],
// [[9, 10], [11, 12, 13]]] // OK
writeln("d = ", d);
// [[[1, 2, 3], [4, 15, 18, 21, 8]],
// [[9, 10], [11, 12, 13]]] // OK
}
Ali
