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digitalmars.D.learn - foreach( i, e; a) vs ndslice

reply Jay Norwood <jayn prismnet.com> writes:
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);

}
Jan 18
parent Ilya Yaroshenko <ilyayaroshenko gmail.com> writes:
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
Jan 19