Question

Suppose option Strict On; a and b – Integers

Dim mySingle as Single = a / b  ' implicit conversion error

Solution A)

Dim mySingle as Single = CSng(a / b)  ' CSng

Solution B)

Dim mySingle as Single = a * 1F / b  ' x 1F

What solution is preferable?
What solution to take if performance is important?

Answer 1

For readability and revealing intent, I would go with A:

Dim mySingle as Single = CSng(a / b)  ' CSng

Using A, you are clearly saying, I know the calculation returns a different type and that’s what I want.

As for performance – I ran a quick micro-benchmark testing 1 million iterations for each and the difference was in the millisecond to sub-millisecond level, with a very slight advantage to CSing. Don’t worry about performance for this kind of conversions (of course, you need to test this on your own).

Benchmark code:

Sub Main()
    Dim mySingle As Single
    Dim a As Integer = 10
    Dim b As Integer = 5

    Dim iterations As Integer = 1000000

    Dim sw As New Stopwatch()

    sw.Start()
    For i As Integer = 1 To iterations
        mySingle = CSng(a / b)  ' CSng '
    Next
    sw.Stop()

    Console.WriteLine(String.Format("CSng(a / b) - {0}", sw.Elapsed))


    sw.Reset()
    sw.Start()
    For i As Integer = 1 To iterations
        mySingle = a * 1.0F / b  ' x 1F '
    Next
    sw.Stop()

    Console.WriteLine(String.Format(" a * 1.0F / b - {0}", sw.Elapsed))

End Sub