Option Explicit
Dim I As Long, J As Long
'字符串匹配的KMP算法
Private Sub Command1_Click()
'* 需匹配的字节数组
Dim P() As Byte
'* 源文件字节数组
Dim S() As Byte
Dim txt As String
Dim Fnum As Long
txt = App.Path & "\Sample"
Fnum = FreeFile
Open txt For Binary As #Fnum
ReDim S(1 To FileLen(txt))
Get #Fnum, , S
Close #Fnum
ReDim P(1 To Len(Text1.Text) / 2)
For I = 1 To Len(Text1.Text) / 2
P(I) = CInt("&H" & Mid(Text1.Text, I * 2 - 1, 2))
Next
Print InByteArray(CInt(Text2.Text), P(), S())
End Sub
'*************************************************************************
'**函 数 名：InStrByteArray
'**输 入：P()(Byte) - 需匹配的字节数组
'** ：S()(Byte) - 源文件字节数组
'**输 出：(Long) - 在源文件中匹配的位置
'**功能描述：字符串匹配的KMP算法，本函数用在字节数组中
'**全局变量：
'**调用模块：
'**作 者：不详
'**日 期：2004年07月17日
'**修 改 人：
'**日 期：
'**版 本：V1.0
'*************************************************************************
Function InByteArray(Start As Long, P() As Byte, S() As Byte) As Long
'*失败联接数组
Dim FLink() As Long
Dim pLen As Long
Dim sLen As Long
Dim flag As Boolean
pLen = UBound(P)
sLen = UBound(S)
ReDim FLink(1 To pLen)
'*KMP算法实现
'*先求得失败联接数组．设FLink(i-1)=j 则有：
'______________________________________
'* P1 P2 P3 ... Pj-1 || Pj
'* Pi-j Pi-j+1 Pi-j+2 ... Pi-2 || Pi-1
'如果Pj=Pi-1则有FLink(i)=FLink(i-1)+1
'如果Pj<>Pi-1则，找寻P的初始子串，使它与Pi-1结束的子串相匹配
'-----------------------------------------
FLink(1) = 0
For I = 2 To pLen
J = FLink(I - 1)
If J <> 0 Then
Do While P(J) <> P(I - 1)
J = FLink(J)
If J = 0 Then Exit Do
Loop
End If
FLink(I) = J + 1
Next
'-----------------------------------------
I = 1: J = 1: flag = False
For I = Start To sLen
If P(J) <> S(I) Then J = FLink(J)
If J = pLen Then
flag = True
Exit For
Else
J = J + 1
End If
Next
If flag = True Then
I = I - pLen + 1
Else
I = 0
End If
InByteArray = I
End Function
