Copy List Of String to another List Of String

Question

Hello

I need to know the difference between the 3 paths to my goal:

Dim MyList as New List(Of String)
MyList.Add(str1) ... and so on ...

Dim NewList As New List(Of String)

Now I have 3 ways:

1 NewList.AddRange(ResumeFailed)
2 NewList.AddRange(ResumeFailed.ToList)
3 NewList.AddRange(ResumeFailed.ToArray)

Thanks :)

Answer 1

'1 NewList.AddRange(ResumeFailed)
NewList.AddRange(ResumeFailed)

'2 NewList.AddRange(ResumeFailed.ToList)   
Dim list As List(Of String) = ResumeFailed.ToList() ' System.Linq Extension Methods
NewList.AddRange(list)

'3 NewList.AddRange(ResumeFailed.ToArray)
Dim array As String() = ResumeFailed.ToArray()      ' List<T>.ToArray
NewList.AddRange(array)

The fastest are 1, 3, and 2. But the fastest one is:

'4 new NewList(ResumeFailed)
Dim NewList As New List(Of String)(ResumeFailed)

This is a sample to measure performance.Please try running it.

Module Program

    Sub Main()

        Const count As Integer = 100000
        Dim MyList As New List(Of String)
        MyList.AddRange(Enumerable.Repeat("AAAA", 10000))

        Watch("1 NewList.AddRange(MyList)",
              Sub()
                  Dim tmp As New List(Of String)
                  tmp.AddRange(MyList)
              End Sub, count)
        Watch("2 NewList.AddRange(MyList.ToList)",
              Sub()
                  Dim tmp As New List(Of String)
                  tmp.AddRange(MyList.ToList)
              End Sub, count)
        Watch("3 NewList.AddRange(MyList.ToArray)",
              Sub()
                  Dim tmp As New List(Of String)
                  tmp.AddRange(MyList.ToArray)
              End Sub, count)
        Watch("4 new NewList(MyList)",
              Sub()
                  Dim tmp As New List(Of String)(MyList)
              End Sub, count)

    End Sub

    Sub Watch(msg As String, action As Action, count As Integer)
        Dim sw As New Stopwatch()
        sw.Start()
        For i = 1 To count
            action.Invoke()
        Next
        sw.Stop()
        Console.WriteLine($"{msg.PadRight(40)} : {sw.Elapsed}")
    End Sub

End Module