C# ToDictionary lambda select index and element?

Question

I have a string like string strn = \"abcdefghjiklmnopqrstuvwxyz\" and want a dictionary like:

Dictionary(){
    {\'a\',0},
    {         


        

Answer 1

What am I doing wrong?

You're assuming there is such an overload. Look at Enumerable.ToDictionary - there's no overload which provides the index. You can fake it though via a call to Select:

var dictionary = text.Select((value, index) => new { value, index })
                     .ToDictionary(pair => pair.value,
                                   pair => pair.index);