Hi

Please consider (1):

void main() {
   import std.stdio;

   int wk_Idx;

   int[2] IntArr;

   IntArr[0] = 1;
   IntArr[1] = 2;

   for (wk_Idx = 0; wk_Idx <= 1; wk_Idx = wk_Idx + 1) {

      writeln("wk_Idx = ", wk_Idx, " IntArr = ", IntArr[wk_Idx]);
   }
}

Now consider (2), which is (1) via assoc. array:

void main() {
   import std.stdio;

   int wk_Idx;

   int[int] IntArr;

   IntArr[0] = 1;
   IntArr[1] = 2;

   for (wk_Idx = 0; wk_Idx <= 1; wk_Idx = wk_Idx + 1) {

      writeln("wk_Idx = ", wk_Idx, " IntArr = ", IntArr[wk_Idx]);
   }
}

And finally (3) which is (2) via a foreach:

void main() {
   import std.stdio;

   int wk_Idx;

   int[int] IntArr;

   IntArr[0] = 1;
   IntArr[1] = 2;

   foreach (wk_Idx; IntArr.keys) {

      writeln("wk_Idx = ", wk_Idx, " IntArr = ", IntArr[wk_Idx]);
   }
}

(1) & (2) compile and run with the expected results.
But (3) fails with:

Error: variable `wk_Idx` is shadowing variable `for3.main.wk_Idx`

Why is this usage wrong?

On Wednesday, 1 March 2023 at 19:05:10 UTC, DLearner wrote:

Error: variable `wk_Idx` is shadowing variable `for3.main.wk_Idx`

With foreach, you can't reuse an existing variable as the loop variable. It always declares a new one. If you want to reuse an existing variable for your loop, you have to use for.

On Wednesday, 1 March 2023 at 19:05:10 UTC, DLearner wrote:

Error: variable `wk_Idx` is shadowing variable `for3.main.wk_Idx`

Or use the each template which is almost the same as foreach to avoid the shadowing variable issue.

import std.algorithm, std.range, std.stdio;

enum len = 10;
void main()
{
  int[len] IntArr, i, n;
  len.iota.each!((i, n) => IntArr[i] = n);

  IntArr.writeln; // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  assert(IntArr == len.iota.array);
}

SDB@79