Question

I have a problem…
I am trying to put into a list of String dictionary keys values if condition of containsvalue is true:

But, this is not correct 🙁

here is a code:

Private listID As New List(Of String)                       ' declaration of list
Private dictionaryID As New Dictionary(Of String, Integer)  ' declaration of dictionary

  'put a keys and values to dictionary
  dictionaryID.Add("first", 1)
  dictionaryID.Add("second", 2)
  dictionaryID.Add("first1", 1)


    If dictionaryID.ContainsValue(1) Then                 ' if value of dictinary is 1
        Dim pair As KeyValuePair(Of String, Integer)
        listID.Clear()
        For Each pair In dictionaryID
            listID.Add(pair.Key)
        Next
    End If

And now, list must have two elements… -> “first” and “first1”

Can you help me?
Thank you very much!

Answer 1

You are looping through the whole dictionary and add all the elements to the list. You should put an if statement in the For Each or use a LINQ query like this:

If listID IsNot Nothing Then
    listID.Clear()
End If
listID = (From kp As KeyValuePair(Of String, Integer) In dictionaryID
          Where kp.Value = 1
          Select kp.Key).ToList()

Using an if statement:

listID.Clear()
For Each pair As KeyValuePair(Of String, Integer) In dictionaryID
    If pair.Value = 1 Then
        listID.Add(pair.Key)
    End If
Next