创建文件应使用什么样的语句啊?
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'文件操作
Close #1close #1'#1是文件记录号
将数据写入一个文件。该函数比lwrite函数要灵活的多。也可将这个函数应用于对通信设备、管道、套接字以及邮槽的处理
Long,TRUE(非零)表示成功,否则返回零。会设置GetLastErrorhFile ---------- Long,一个文件的句柄 lpBuffer ------- Any,要写入的一个数据缓冲区 nNumberOfBytesToWrite - Long,要写入数据的字节数量。如写入零字节,表示什么都不写入,但会更新文件的“上一次修改时间”。针对位于远程系统的命名管道,限制在65535个字节以内 lpNumberOfBytesWritten - Long,实际写入文件的字节数量 lpOverlapped --- OVERLAPPED,倘若在指定FILE_FLAG_OVERLAPPED的前提下打开文件,这个参数就必须引用一个特殊的结构。那个结构定义了一次异步写操作。否则,该参数应置为空(将声明变为ByVal
As Long,并传递零值)并不是每种操作系统都支持在任何类型的设备上进行异步操作。windows
95不支持对磁盘文件的重叠读取操作
'Read and Write
Const MOVEFILE_REPLACE_EXISTING = &H1
Const FILE_ATTRIBUTE_TEMPORARY = &H100
Const FILE_BEGIN = 0
Const FILE_SHARE_READ = &H1
Const FILE_SHARE_WRITE = &H2
Const CREATE_NEW = 1
Const OPEN_EXISTING = 3
Const GENERIC_READ = &H80000000
Const GENERIC_WRITE = &H40000000
Private Declare Function SetVolumeLabel Lib "kernel32" Alias "SetVolumeLabelA" (ByVal lpRootPathName As String, ByVal lpVolumeName As String) As Long
Private Declare Function WriteFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, lpNumberOfBytesWritten As Long, ByVal lpOverlapped As Any) As Long
Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, ByVal lpOverlapped As Any) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Any, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function SetFilePointer Lib "kernel32" (ByVal hFile As Long, ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, ByVal dwMoveMethod As Long) As Long
Private Declare Function SetFileAttributes Lib "kernel32" Alias "SetFileAttributesA" (ByVal lpFileName As String, ByVal dwFileAttributes As Long) As Long
Private Declare Function GetFileSize Lib "kernel32" (ByVal hFile As Long, lpFileSizeHigh As Long) As Long
Private Declare Function GetTempFileName Lib "kernel32" Alias "GetTempFileNameA" (ByVal lpszPath As String, ByVal lpPrefixString As String, ByVal wUnique As Long, ByVal lpTempFileName As String) As Long
Private Declare Function MoveFileEx Lib "kernel32" Alias "MoveFileExA" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal dwFlags As Long) As Long
Private Declare Function DeleteFile Lib "kernel32" Alias "DeleteFileA" (ByVal lpFileName As String) As Long
Private Sub Form_Load()
'KPD-Team 1998
'URL: http://www.allapi.net/
'E-Mail: [email protected]
Dim sSave As String, hOrgFile As Long, hNewFile As Long, bBytes() As Byte
Dim sTemp As String, nSize As Long, Ret As Long
'Ask for a new volume label
sSave = InputBox("Please enter a new volume label for drive C:\" + vbCrLf + " (if you don't want to change it, leave the textbox blank)")
If sSave <> "" Then
SetVolumeLabel "C:\", sSave
End If 'Create a buffer
sTemp = String(260, 0)
'Get a temporary filename
GetTempFileName "C:\", "KPD", 0, sTemp
'Remove all the unnecessary chr$(0)'s
sTemp = Left$(sTemp, InStr(1, sTemp, Chr$(0)) - 1)
'Set the file attributes
SetFileAttributes sTemp, FILE_ATTRIBUTE_TEMPORARY
'Open the files
hNewFile = CreateFile(sTemp, GENERIC_WRITE, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0)
hOrgFile = CreateFile("c:\config.sys", GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0) 'Get the file size
nSize = GetFileSize(hOrgFile, 0)
'Set the file pointer
SetFilePointer hOrgFile, Int(nSize / 2), 0, FILE_BEGIN
'Create an array of bytes
ReDim bBytes(1 To nSize - Int(nSize / 2)) As Byte
'Read from the file
ReadFile hOrgFile, bBytes(1), UBound(bBytes), Ret, ByVal 0&
'Check for errors
If Ret <> UBound(bBytes) Then MsgBox "Error reading file ..." 'Write to the file
WriteFile hNewFile, bBytes(1), UBound(bBytes), Ret, ByVal 0&
'Check for errors
If Ret <> UBound(bBytes) Then MsgBox "Error writing file ..." 'Close the files
CloseHandle hOrgFile
CloseHandle hNewFile 'Move the file
MoveFileEx sTemp, "C:\KPDTEST.TST", MOVEFILE_REPLACE_EXISTING
'Delete the file
DeleteFile "C:\KPDTEST.TST"
Unload Me
End Sub
能够对文件输入/输出 (I/O)。语法Open pathname For mode [Access access] [lock] As [#]filenumber [Len=reclength]Open 语句的语法具有以下几个部分:部分 描述
pathname 必要。字符串表达式,指定文件名,该文件名可能还包括目录、文件夹及驱动器。
mode 必要。关键字,指定文件方式,有 Append、Binary、Input、Output、或 Random 方式。如果未指定方式,则以 Random 访问方式打开文件。
access 可选。关键字,说明打开的文件可以进行的操作,有 Read、Write、或 Read Write 操作。
lock 可选。关键字,说明限定于其它进程打开的文件的操作,有 Shared、Lock Read、Lock Write、和 Lock Read Write 操作。
filenumber 必要。一个有效的文件号,范围在 1 到 511 之间。使用 FreeFile 函数可得到下一个可用的文件号。
reclength 可选。小于或等于 32,767(字节)的一个数。对于用随机访问方式打开的文件,该值就是记录长度。对于顺序文件,该值就是缓冲字符数。
说明对文件做任何 I/O 操作之前都必须先打开文件。Open 语句分配一个缓冲区供文件进行 I/O 之用,并决定缓冲区所使用的访问方式。如果 pathname 指定的文件不存在,那么,在用 Append、Binary、Output、或 Random 方式打开文件时,可以建立这一文件。如果文件已由其它进程打开,而且不允许指定的访问类型,则 Open 操作失败,而且会有错误发生。如果 mode 是 Binary 方式,则 Len 子句会被忽略掉。重要 在 Binary、Input 和 Random 方式下可以用不同的文件号打开同一文件,而不必先将该文件关闭。在 Append 和 Output 方式下,如果要用不同的文件号打开同一文件,则必须在打开文件之前先关闭该文件。
本示例示范 Open 语句的不同用法来做到文件的输出与输入。下列代码以顺序输入模式打开 TESTFILE 文件。Open "TESTFILE" For Input As #1
' 若要以其他方式打开文件,必需先关闭此文件。
Close #1下列代码以只允许写操作的二进制方式打开文件。Open "TESTFILE" For Binary Access Write As #1
' 若要以其他方式打开文件,必需先关闭此文件。
Close #1下列代码以随机方式打开文件,文件中含有用户自定义数据类型 Record 的记录。Type Record ' 定义用户自定义数据类型。
ID As Integer
Name As String * 20
End TypeDim MyRecord As Record ' 声明变量。
Open "TESTFILE" For Random As #1 Len = Len(MyRecord)
' 若要以其他方式打开文件,必需先关闭此文件。
Close #1下列代码以顺序输出方式打开文件;任何过程都可以读写该文件。Open "TESTFILE" For Output Shared As #1
' 若要以其他方式打开文件,必需先关闭此文件。
Close #1下列代码以只允许读的二进制方式打开文件;其他过程不可以读该文件。Open "TESTFILE" For Binary Access Read Lock Read As #1