Question

I’m working with a dictionary(of string, list(of string)) in VB to store some text data pulled from large .csv files.

The dictionary.key is just a date string like “2012-12-12”, and the corresponding list value contains all of the files that are associated with that date.

Using a StreamReader and a line.split, I can pull out the date string and compare it to the dictionary. If the dictionary does not contain that date, I want to insert it as a new key, then add the filename to the list for that key. This will loop through the whole file, then continue through every file the user has selected, using the same dictionary. Eventually I should see 4 or 5 file names per date, with no duplicate file names per date allowed.

What is the correct way to use dictionary.add method to do this?

Answer 1

something like this?

Dim key as String = "asdf"
If Not dict.ContainsKey(key) Then
    dict.Add(key, New List(Of String)(New String() {"1", "2", "3"}))
    Dim values = dict(key)
    If not values.Contains("some value") Then
        values.Add("some value")
    End If
End If

or something like this:

Dim key as String = "asdf"
If Not dict.ContainsKey(key) Then
    dict.Add(key, New List(Of String))
    dict(key).Add("1")
    dict(key).Add("2")
    ... and however many more values here ...
End If