Question

I want to set an String in one Line with help of .SelectMany().
I have an Object, which holds an Dictionary<String,FileInfo>. For each element into these Dictionary I want to got the Key to put into String.Format(), but i always get "System.Linq.Enumerable+<SelectManyIterator>d__142[System.String,System.Char]" as returnvalue.

Where is my fault?

String.Format(
    "All Strings : {0} on {1} ", 
    MyObject.MyDictionary.Keys.SelectMany(x => x), 
    MyObject.Type);

Answer 1

The SelectMany will return an IEnumerable, that’s why, you’ll need to get the keys into a string, like so:

String.Format("All Strings : {0} on {1}",
     String.Join(", ", MyObject.MyDictionary.Select(x => x.Key)),
     MyObject.Type);