perftests.vb

来自「Microsoft Mobile Development Handbook的代码」· VB 代码 · 共 75 行

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Collections

Namespace CodeForChapter5cs
  Friend Class PerfTests
	#Region "string vs stringbuilder"
	Public Shared Sub UseString()
	  Dim result As String = String.Empty
	  For i As Integer = 0 To 9999
		result &= "string are immutable " & "but I still use them as if they are not"
	  Next i
	End Sub

	Public Shared Sub UseStringBuilder()
	  Dim result As String = String.Empty
	  Dim sb As StringBuilder = New StringBuilder()
	  For i As Integer = 0 To 9999
		sb.Append("string are immutable ").Append("but I still use them as if they are not")
	  Next i

	  result = sb.ToString()
	End Sub
	#End Region

	#Region "Collections test"
	Public Shared Sub UseArrayList()
	  Dim a1 As ArrayList = New ArrayList(100000)
	  Dim a2 As ArrayList = New ArrayList(100000)

	  For i As Integer = 0 To 99999
		a2.Add(i * i) ' boxing
	  Next i

	  For i As Integer = 0 To 99999
		Dim j As Integer = CInt(Fix(a2(i))) 'unboxing
		a1.Add(j) 'boxing
	  Next i

	End Sub

	Public Shared Sub UseGenerics()
	  Dim a1 As List(Of Integer) = New List(Of Integer)(100000)
	  Dim a2 As List(Of Integer) = New List(Of Integer)(100000)

	  For i As Integer = 0 To 99999
		a2.Add(i * i)
	  Next i

	  For i As Integer = 0 To 99999
		Dim j As Integer = a2(i)
		a1.Add(j)
	  Next i
	End Sub

	Public Shared Sub UseArray()
	  Dim a1 As Integer() = New Integer(99999){}
	  Dim a2 As Integer() = New Integer(99999){}

	  For i As Integer = 0 To 99999
		a2(i) = i * i
	  Next i

	  For i As Integer = 0 To 99999
		Dim j As Integer = a2(i)
		a1(i) = j
	  Next i
	End Sub

	#End Region
  End Class
End Namespace