foreach( i, e; a) vs ndslice

[Ilya Yaroshenko via Digitalmars-d-learn]

On Monday, 18 January 2016 at 23:33:53 UTC, Jay Norwood wrote:
> I'm playing with the example below.  I noticed a few things.
> 1. The ndslice didn't support the extra index, i, in the 
> foreach, so had to add extra i,j.
> 2. I couldn't figure out a way to use sliced on the original 
> 'a' array.  Is slicing only available on 1 dim arrays?
> 3. Sliced parameter order is different than multi-dimension 
> array dimension declaration.
>
> import std.stdio;
> import std.experimental.ndslice.slice;
>
> void main() {
>     int[4][5] a = new int[20];
>     foreach(i,ref r; a){
>         foreach(j,ref c; r){
>             c= i+j;
>             writefln("a(%d,%d)=%s",i,j,c);
>         }
>     }
>     writefln("a=%s",a);
>
>     auto b = new int[20].sliced(5,4);
>
>     int i=0;
>     foreach( ref r; b){
>         int j=0;
>         foreach( ref c; r){
>             c= i+j;
>             writefln("b(%d,%d)=%s",i,j,c);
>             j++;
>         }
>         i++;
>     }
>     writefln("b=%s",b);
>
> }

Hi,

1. You can use std.range.enumerate or just use a normal foreach:
   foreach(i; 0..slice.length!0)
   {
     /// use slice[i] ...
   }
2. Yes (A 2D D array is an array of arrays, so slice would be a 
slice composed of arrays)
3. Order is correct:

void main() {
     auto a = new long[][](5, 4);
     auto b = new long[20].sliced(5, 4);
     foreach(i, ref r; a) {
         foreach(j, ref c; r) {
             c = i+j;
             b[i, j] = c;
             writefln("a(%d,%d)=%s", i, j, c);
             writefln("b(%d,%d)=%s", i, j, b[i, j]);
         }
     }
     writefln("a=%s",a);
     writefln("b=%s",b);
}

Ilya