Why is it that when I type "auto choice = randomSample(array);" and later when I try to index choice as in choice[1] it gives an error message?

On 12/27/2018 06:06 PM, Murilo wrote:
> Why is it that when I type "auto choice = randomSample(array);" and
> later when I try to index choice as in choice[1] it gives an error message?

It's because randomSample returns either an input range or a forward range depending both on the kind of range that it gets and the random number generator used. Documented here:

  https://dlang.org/library/std/random/random_sample.html

Because it never returns a random access range, it does not provide indexing with operator []. If you definitely want random access, the normal thing to do is to copy the elements into an array with e.g. std.array.array (imported publicly by std.random):

import std.stdio;
import std.random;
import std.range;

void main() {
    auto array = 100.iota;
    // .array at the end returns an array:
    auto choice = randomSample(array, 10).array;
    writeln(choice[1]);
}

Ali

On Friday, 28 December 2018 at 03:59:52 UTC, Ali Çehreli wrote:
> It's because randomSample returns either an input range or a forward range depending both on the kind of range that it gets and the random number generator used. Documented here:
> Ali
Thank you very much, now it all makes sense.