How to Humanize Numerical Input|Output

[Jabari Zakiya via Digitalmars-d-learn]

I have this code to input integer values:

```
  ulong[] x;
  foreach (_; 0 .. 2) { ulong a; readf!" %d"(a); x ~= a; }
  end_num = max(x[0], 3);
  start_num = max(x[1], 3);
  if (start_num > end_num) swap(start_num, end_num);
  start_num = start_num | 1;             // if start_num even add 
1
  end_num = (end_num - 1) | 1;           // if end_num even 
subtract 1
  if (end_num - start_num < 2) { start_num = 7; end_num = 7; }
```

Currently I have to enter data as:   123456 789102

I'd like to enter data as:  123_456 789_10

How do I do that?

Also for output, I do this:

```
writeln("total twins = ", twinscnt, "; last twin = ", last_twin - 
1, "+/-1");
```

I'd also like to output data as:  123,987 or 123_987