VB 二进制块读写类模块应用实例,包括一个文件拷贝和一个文件二进制比较的例子。

王朝vb·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

文件拷贝实例:(Text1存放源文件位置,Text2存放目标文件位置)------------------------------------------------------------------------

Private Sub Command3_Click()

Const BUFFER_SIZE = 40960 * 2 '规定缓冲区大小

Dim nActual As Long

Dim aBuf(0 To BUFFER_SIZE - 1) As Byte '分配缓冲区

Dim tmr As Single '计时变量

Dim lFileLen As Long '纪录文件长度

Dim iFileNum As Integer '记录文件号

Dim k As Long

tmr = Timer

If Not m_cFileRead.OpenBinary(Text1.Text) Then MsgBox "打开文件失败!" & Text1.Text

If Not m_cFileWrite.OpenBinary(Text2.Text) Then MsgBox "打开文件失败!" & Text2.Text

'记下文件长度和打开文件所用的文件号,是为了优化性能。

lFileLen = m_cFileRead.FileLength

iFileNum = m_cFileRead.FileNumber

k = 0

Do

k = k + 1

If k = 10 Then

k = 0

'pb1是进度条控件。

pb1.Value = 100 * (Seek(iFileNum) / lFileLen) '显示百分比

DoEvents

End If

'读块,传给它缓冲区指针和期望读取的字节数,返回实际读取的字节数,

nActual = m_cFileRead.ReadBlock(VarPtr(aBuf(0)), BUFFER_SIZE)

'写块,传给它缓冲区指针和期望写入的字节数。

m_cFileWrite.WriteBlock VarPtr(aBuf(0)), nActual

Loop Until nActual < BUFFER_SIZE '当实际读取字节数小于缓冲区大小的时候,就不需要再读啦,已读完啦

m_cFileRead.CloseFile '关文件

m_cFileWrite.CloseFile

MsgBox "OK! total time:" & Timer - tmr

End Sub

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二进制文件比较实例(Text1存放第一个文件的位置,Text2存放第二个文件的位置)----------------------------

Private Sub Command2_Click()

Const BUFFER_SIZE As Long = 4096 * 2 '规定缓冲区大小

Dim cfRead1 As New CFileRead

Dim cfread2 As New CFileRead

Dim aBuf1(0 To BUFFER_SIZE - 1) As Byte '分配缓冲区

Dim aBuf2(0 To BUFFER_SIZE - 1) As Byte

Dim nActual As Long

Dim i As Long, lCurPos As Long

Dim tmr As Single

Dim k As Long

tmr = Timer

If Not cfRead1.OpenBinary(Text1.Text) Then MsgBox "open file failed:" & Text1.Text

If Not cfread2.OpenBinary(Text2.Text) Then MsgBox "open file failed:" & Text2.Text

If cfRead1.FileLength <> cfread2.FileLength Then MsgBox "文件不一样长"

lCurPos = 1 '当前待比较字节的位置,虚拟位置,不同于文件的读写指针。

k = 0

Do

'读块,传给它缓冲区指针和期望读取的字节数,返回实际读取的字节数,

nActual = cfRead1.ReadBlock(VarPtr(aBuf1(0)), BUFFER_SIZE)

'读第2个文件的数据块

nActual = cfread2.ReadBlock(VarPtr(aBuf2(0)), BUFFER_SIZE)

For i = 0 To nActual - 1 '比较缓冲区

If aBuf1(i) <> aBuf2(i) Then MsgBox "不同,位置:" & lCurPos: Exit Do

lCurPos = lCurPos + 1 '移到下一个待比较字节的位置

Next i

k = k + 1

If k = 100 Then

k = 0

Cls

Print Timer - tmr, " ", (Seek(cfRead1.FileNumber) / 1024) / (Timer - tmr) & " KB/s"

End If

Loop Until nActual < BUFFER_SIZE

cfRead1.CloseFile '关文件

cfread2.CloseFile

MsgBox "OK! " & Timer - tmr

End Sub

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