Which is more efficient Cstr(value) or value.ToString()

Question

I am wondering which is more efficient, using CStr() or object.toString(). The reason I ask this is because I though all that CStr() done was to invoke the .ToString() metho

Answer 1

Here is the code from the above test, but redone with System.Diagnostics.Stopwatch, and removing the Console.write bottleneck.

It turns out directcasting is fastest(as well it should be - it isn't doing anything in this case. However its a trivialised example because its rare you would want to convert a string to a string. Converting Module Module1 Sub Main()

    Dim obj As Object = "asdfsdasdfsadfasdfasdfasdfsdasdfsadfasdfasdfdafsdfasd"
    Dim LL As New List(Of String), SWW As System.Diagnostics.Stopwatch

    LL.Clear()

    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        LL.Add(obj.ToString)
    Next
    Console.WriteLine("obj.ToString took {0}.", SWW.ElapsedTicks)

    LL.Clear()
    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        LL.Add(CStr(obj))
    Next
    Console.WriteLine("CStr(obj) took {0}.", SWW.ElapsedTicks)

    LL.Clear()
    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        LL.Add(DirectCast(obj, String))
    Next
    Console.WriteLine("DirectCast(obj, String) took {0}.", SWW.ElapsedTicks)





    Console.WriteLine("---------------- Integer To String ----------- ")

    obj = 15522

    LL.Clear()
    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        LL.Add(obj.ToString)
    Next
    Console.WriteLine("obj.ToString took {0}.", SWW.ElapsedTicks)

    LL.Clear()
    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        LL.Add(CStr(obj))
    Next
    Console.WriteLine("CStr(obj) took {0}.", SWW.ElapsedTicks)

    LL.Clear()
    SWW = Stopwatch.StartNew()
    For i = 0 To Short.MaxValue
        Dim str As String = TryCast(obj, String)
        ' This obviously fails, as obj is not a string, which is why it is so fast.. str is then nothing
        LL.Add(str)

    Next
    Console.WriteLine("DirectCast(obj, String) took {0}.", SWW.ElapsedTicks)

    Console.Read()
End Sub

End Module

My results:

(string ) : ToString : 2288; CStr: 2275; DirectCast: 1586

(integer) : ToString : 10526; CStr: 13184; TryCast: 982