vbs的字符串操作效率分析总结

<%
'vbs版高速字符串操作代码演示
'淮南子编写
Option explicit
Dim StrTime,EndTime
Dim MyString,MyArray,ArrayIndexCount,CurIndex
Const TestNumber = 9999 '循环次数
StrTime = Timer()
'============测试开始============
'代码执行效率
'本人机器配置:
'CPU: 酷睿双核2250 CPU频率:1.73G
'内存: 1GB
'请逐一开启方法进行测试
'StringLinkTest1() '性能最差，大约耗时20秒
'StringLinkTest2() '性能大大改善,大约耗时0.2秒
'StringArrayTest() '性能最佳，大约耗时0.06秒
'============测试结束============
'输出结果
'Response.Write MyString
EndTime = Timer()
Response.Write "耗时:" & FormatNumber((EndTime-StrTime) * 1000,3) & " 毫秒"
'字符串操作函数，淮南子原创
Sub Add(Value)
If (CurIndex >= ArrayIndexCount) Then
ArrayIndexCount = CurIndex * 1.1 '如果欲添加项超出数组下标，则将数组容量扩增百分之10
ReDim Preserve MyArray(ArrayIndexCount)
End If
MyArray(CurIndex) = Value
CurIndex = CurIndex + 1
End Sub
'测试方法
'使用数组进行字符串叠加，在所有方法中，该方法性能最佳(效率较StringLinkTest2()的方法提升了近4倍)
Sub StringArrayTest()
ArrayIndexCount = 20
CurIndex = 0
ReDim MyArray(ArrayIndexCount)
Dim i
For i = 0 to TestNumber
Add "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
Next
MyString = Join(MyArray,"")
End Sub
'测试方法1
'常规的字符串连接
Sub StringLinkTest1()
Dim i,str
dim a1
a1 = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
For i=0 to TestNumber
'常规字符串连接
Str=(Str&a1)
Next
MyString = Str
End Sub
'测试方法2
'在常规的字符串连接方式中，使用临时变量来提速 ,效率较StringLinkTest1()的方法提升了近100倍
Sub StringLinkTest2()
Dim i,str,a1,TmpString
a1 = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
For i=0 to TestNumber
'使用临时变量提速
TmpString = (TmpString & a1)
'每二百次则进行一次累计
If i mod 200 = 0 Then
'保存临时变量值
Str = (Str & TmpString)
'清空临时变量值
TmpString = ""
End If
Next
if TmpString<>"" Then MyString = (Str & TmpString)
End Sub
%>

'最简单的例子，生成num个重复的str，例如 XString(5,"<br>") '输出: <br><br><br><br><br>
Function XString(num,str)
On Error Resume Next
Dim i,a
Redim a(num-1)
For i=0 To num-1
a(i)=str
Next
XString=Join(a,"")
On Error GoTo 0
End Function


'字符串拼接类公共版
Class clsStrCat
Private aFStrings()
Private iFSPos,iFSLen,iFSIncr
Private Sub Class_Initialize()
On Error Resume Next
iFSIncr = STRCATBUF
If Err Then iFSIncr = 200 : Err.Clear
Reset
On Error GoTo 0
End Sub
Private Sub Class_Terminate()
Erase aFStrings
End Sub
Public Property Let Item(ByRef sData)
If iFSPos > iFSLen Then
iFSLen = iFSPos + iFSIncr
ReDim Preserve aFStrings(iFSLen)
End If
aFStrings(iFSPos) = sData
iFSPos = iFSPos + 1
End Property
Public Default Property Get Item()
Item = Join(aFStrings, "")
End Property
Public Sub Reset()
iFSPos = 0
iFSLen = iFSIncr
ReDim aFStrings(iFSLen)
End Sub
Public Sub Resize(n)
If Not IsNumeric(n) Then Exit Sub
iFSPos = 0
iFSIncr = n
iFSLen = iFSIncr
ReDim aFStrings(iFSLen)
End Sub
Public Property Get Strs()
Strs=aFStrings
End Property
Public Property Get Count()
Count=iFSPos
End Property
Public Property Get IsInit()
If iFSPos=0 Then IsInit=True Else IsInit=False
End Property
End Class