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Siebel VB Language Reference > VB Language Reference >
Open Statement
This standard VB statement opens a file for input or output. Syntax
Open filename [For mode] [Access access] [lock] As [#]filenumber [Len = reclen]
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filename |
A string or string expression representing the name of the file to open |
mode |
A keyword indicating the purpose for which the file is opened |
access |
A keyword indicating the method of access to the file |
lock |
A keyword designating the access method allowed to the file by other processes |
filenumber |
An integer used to identify the file while it is open |
reclen |
In a Random or Binary file, the length of the records |
Returns
A file opened in the specified manner. NOTE: The file opens in the default code page of the local operating system. File I/O does not support Unicode.
Usage
The following keywords are used for mode, access, and lock:
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Mode Keywords |
Input |
Reads data from the file sequentially |
Output |
Puts data into the file sequentially |
Append |
Adds data to the file sequentially |
Random |
Gets data from the file by random access |
Binary |
Gets binary data from the file |
Access Keywords |
Read |
Reads data from the file only |
Write |
Writes data to the file only |
Read Write |
Reads or writes data to the file |
Lock Keywords |
Shared |
Read or write is available on the file |
Lock Read |
Only read is available |
Lock Write |
Only write is available |
Lock Read Write |
No read or write is available |
A file must be opened before any input/output operation can be performed on it. If filename does not exist, it is created when opened in append, binary, output, or random modes. If mode is not specified, it defaults to random. If access is not specified for random or binary modes, access is attempted in the following order: Read Write, Write, Read. If lock is not specified, filename can be opened by other processes that do not specify a lock, although that process cannot perform any file operations on the file while the original process still has the file open. Use the FreeFile function to find the next available value for filenumber. The reclen argument is ignored for Input, Output, and Append modes. Example
This example opens a file for random access, gets the contents of the file, and closes the file again. The second subprogram, CreateFile, creates the file c:\temp001 used by the main subprogram. (general) (declarations)
Option Explicit
Declare Sub CreateFile
Sub CreateFile
' Put the numbers 1-10 into a file
Dim x as Integer
Open "c:\temp001" for Output as #1
For x = 1 to 10
Write #1, x
Next x
Close #1
End Sub
Sub Button_Click
Dim acctno as String * 3
Dim recno as Long
Dim msgtext as String
Call CreateFile
recno = 1
newline = Chr(10)
Open "c:\temp001" For Random As #1 Len = 3
msgtext = "The account numbers are:" & newline
Do Until recno = 11
Get #1,recno,acctno
msgtext = msgtext & acctno
recno = recno + 1
Loop
Close #1
Kill "c:\temp001"
End Sub
See Also
Close Statement
FreeFile Function
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