Visual-Studio-2008 – In VB 2008, why does the short circuit need to be longer than the integer?

Sub Button1_Click(sender As Object, ByVal e As EventArgs) Handles Button1.Click< br /> Dim stopwatch1, stopwatch2 As New Stopwatch: Dim EndLoop As ULong = 10000

 stopwatch1.Start()
 For cnt As ULong = 1 To EndLoop
 Dim Number1 As UInt32 
 For Number1 = 1 To 20000
 Dim Number2 As UInt32 = 0
 Number2 += 1
 Next
 Next
 stopwatch1.Stop()

 stopwatch2.Start()
 For cnt As ULong = 1 To EndLoop
 Dim Number1 As UShort
 For Number1 = 1 To 20000
 Dim Number2 As UShort = 0 
 Number2 += 1
 Next
 Next
 stopwatch2.Stop()

 Label1.Text = "UInt32: "& stopwatch1.ElapsedMilliseconds
 Label2.Text = "UShort: "& stopwatch2.ElapsedMilliseconds
End Sub

stopwatch2.Start( )
For cnt As ULong = 1 To EndLoop
 Dim Number1 As Integer
 For Number1 = 1 To 20000
 Dim Number2 As Integer = 0
 Number2 += 1< br /> Next
Next
stopwatch2.Stop()

In this example:

Sub Button1_Click(sender As Object, ByVal e As EventArgs) Handles Button1.Click
 Dim stopwatch1, stopwatch2 As New Stopwatch: Dim EndLoop As ULong = 10000

 stopwatch1.Start()
 For cnt As ULong = 1 To EndLoop
 Dim Number1 As UInt32
 For Number1 = 1 To 20000
 Dim Number2 As UInt32 = 0
 Number2 += 1
 Next
 Next
 stopwatch1.Stop ()

 stopwatch2.Start()
 For cnt As ULong = 1 To EndLoop
 Dim Number1 As UShort
 For Number1 = 1 To 20000
 Dim Number2 As UShort = 0
 Number2 += 1
 Next
 Next
 stopwatch2.Stop()

 Label1.Text = "UInt32: "& stopwatch1.ElapsedMilliseconds
 Label2.Text = "UShort:" & stopwatch2.ElapsedMilliseconds
End Sub

For the UInt32 loop, I keep getting about 950 milliseconds, and for the UShort loop, it takes about 1900 milliseconds. If I change UShort to Short, I also get about 1900 ms.

In addition, I You can change the second loop to:

stopwatch2.Start()
For cnt As ULong = 1 To EndLoop
 Dim Number1 As Integer
 For Number1 = 1 To 20000
 Dim Number2 As Integer = 0
 Number2 += 1
 Next
Next
stopwatch2.Stop()

< p>The integer loop will always be 660 ms, and the UInt32 loop will be 950 ms.

Compared with Short, UShort and UInt32, is the data type used by Integers faster? If so, why?

I bet this is because the natural word size on your machine is 32 bits, and 16-bit operations will actually put more pressure on the system To cut and mask these bits.

If you test on a 64-bit processor, the results of Int64 may be better than Int32…

In addition, in .NET , All integer (up to 32 bits) arithmetic will be automatically upgraded to int, so when you assign the result back to a short variable, you will cause an extra conversion step. The same applies to uint.