<%
'vbs版高速字符串操作代碼演示
'淮南子編寫(xiě)
Option explicit
Dim StrTime,EndTime
Dim MyString,MyArray,ArrayIndexCount,CurIndex
Const TestNumber = 9999 '循環(huán)次數(shù)
StrTime = Timer()
'============測(cè)試開(kāi)始============
'代碼執(zhí)行效率
'本人機(jī)器配置:
'CPU: 酷睿雙核2250 CPU頻率:1.73G
'內(nèi)存: 1GB
'請(qǐng)逐一開(kāi)啟方法進(jìn)行測(cè)試
'StringLinkTest1() '性能最差，大約耗時(shí)20秒
'StringLinkTest2() '性能大大改善,大約耗時(shí)0.2秒
'StringArrayTest() '性能最佳，大約耗時(shí)0.06秒
'============測(cè)試結(jié)束============
'輸出結(jié)果
'Response.Write MyString
EndTime = Timer()
Response.Write "耗時(shí):" & FormatNumber((EndTime-StrTime) * 1000,3) & " 毫秒"
'字符串操作函數(shù)，淮南子原創(chuàng)
Sub Add(Value)
If (CurIndex >= ArrayIndexCount) Then
ArrayIndexCount = CurIndex * 1.1 '如果欲添加項(xiàng)超出數(shù)組下標(biāo)，則將數(shù)組容量擴(kuò)增百分之10
ReDim Preserve MyArray(ArrayIndexCount)
End If
MyArray(CurIndex) = Value
CurIndex = CurIndex + 1
End Sub
'測(cè)試方法
'使用數(shù)組進(jìn)行字符串疊加，在所有方法中，該方法性能最佳(效率較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
'測(cè)試方法1
'常規(guī)的字符串連接
Sub StringLinkTest1()
Dim i,str
dim a1
a1 = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
For i=0 to TestNumber
'常規(guī)字符串連接
Str=(Str&a1)
Next
MyString = Str
End Sub
'測(cè)試方法2
'在常規(guī)的字符串連接方式中，使用臨時(shí)變量來(lái)提速 ,效率較StringLinkTest1()的方法提升了近100倍
Sub StringLinkTest2()
Dim i,str,a1,TmpString
a1 = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
For i=0 to TestNumber
'使用臨時(shí)變量提速
TmpString = (TmpString & a1)
'每二百次則進(jìn)行一次累計(jì)
If i mod 200 = 0 Then
'保存臨時(shí)變量值
Str = (Str & TmpString)
'清空臨時(shí)變量值
TmpString = ""
End If
Next
if TmpString<>"" Then MyString = (Str & TmpString)
End Sub
%>

'最簡(jiǎn)單的例子，生成num個(gè)重復(fù)的str，例如 XString(5,"<br>") '輸出: <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


'字符串拼接類(lèi)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