For each get RowIndex

Question

Is there a way in a for each to get the row index ?

Example :

int rowIndex = 0;
foreach (int a in numbers)
{
    // Manipulation
    rowIndex++;
}

What I would like to have

foreach (int a in numbers)
{
    a.RowIndex;
}

Is there a quick way of doing it ? Maybe with the use of extension methods ?

Answer 1

Try the following

foreach ( var item in numbers.Select( (x,i) => new { Index = i, Value = x })) {
  var index = item.Index;
  var value = item.Value;
  ...
}

There is an overload of select which passes down the index of the item. This code will create a new anonymous type for every item which includes both the index and the value.

Here's an alternate way which makes the syntax slightly more readable.

public static void ForEach<T>(this IEnumerable<T> source, Action<T,int> del) {
  int i = 0;
  foreach ( var cur in source ) { 
    del(cur, i);
    i++;
  }
}

numbers.ForEach( (x,i) =>
{
  // x is the value and i is the index
}

This doesn't add a whole lot over the define a local and increment it manually solution. Is there a particular reason you don't want to do it that way?

Answer 2

Duplicate of this question?

Answer 3

This is probably the simplest way, if you're going to stick to a foreach loop. Nothing level, but I think it's the best way to go still.

int rowIndex = 0;
foreach (int a in numbers)
{
    rowIndex++; // You could of course inline this wherever rowIndex first
                // gets used, and then simply reference rowIndex (without
                // the increment) later.

    // ...
}

But once you start doing this, it's probably best just to use an ordinary for loop anyway (unless you can't because the collection only implements IEnumerable and not IList/ICollection of course).