linq projection element count

Question

Suppose:

var a = SomeCollection.OrderBy(...)
              .Select(f => new MyType
                               {
                                  counter = ? //I want counter value, so what first
                                              //object have counter=1, second counter=2 
                                              //and so on
                                  a=f.sometthing,
                                  ...
                                });

How do I set this counter value? Or do I fave to iterate a afterwards?

Answer 1

Use the overload of Select that gives you the current element's 0-based index.

.Select((item, index) => new MyType
            { 
                counter = index + 1,
                a = item.Something

Answer 2

Simply capture a variable:

int index = 1;

var a = SomeCollection.OrderBy(...)
        .Select(x => new MyType { counter = index++; });

The counter will increment as each iteration is called.