Question

I have a

List<string> myList = new List<string>();

telling me all of the things I should find in some input data. I’d like to convert this into a

Dictionary<string, bool> myDict = Dictionary<string, bool>();

where the dictionary keys are the same as the list entries, and all the values are false. I’ll then run over the data, and update the dictionary value when I find the elements.

This seems simple, but

Dictionary<string, bool> myDict = myList.ToDictionary<string, bool>(x => false);

doesn’t work because of an error:

Cannot implicitly convert type Dictionary<bool, string> to Dictionary<string, bool>

Answer 1

You want to do something like this:

var dict = myList.ToDictionary(s => s, s => false);

The overload that you were using will create a Dictionary<bool, string>, with key being bool and value the string values from the list. ( And having bool as key will mean, you can have only two entries 😉

Also, you rarely need to specify the type parameters like <string, bool> to methods explcitly, as they can be inferred, and you can use var for variables, like done above.