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open as binary

Hello, is there any ppl tell me that what is the use of open as binary ?? And can give me an complete and simplest example of how to use this ??
Thanks in advance !
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ahchong
Asked:
ahchong
1 Solution
 
RuchiCommented:
The binary files are accessed byte by byte.

'Fill the string variable MyString with the string "This is a test"
MyString = "This is a test"

'Get a free file number
FileNum = FreeFile

'Open the file Test.Txt for binary access
Open "Test.txt" For Binary As FileNum

'Write the sstring variable MyString, starting at byte location 100
Put #FileNum, 100, MyString

'close the file
Close FileNum
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RuchiCommented:
When you open a file for binary access , you can read from and write to any byte location in the file.

Hope this helps.
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RuchiCommented:
This is a very small program. Place a command button on the form.

Option Explicit

Private Sub Command1_Click()

Dim MyString As String
Dim FileNum As Integer
'Fill the string variable MyString with the string "This is a test"
MyString = "This is a test"

'Get a free file number
FileNum = FreeFile

'Open the file Test.Txt for binary access
Open "C:\Test1.txt" For Binary As FileNum

'Write the sstring variable MyString, starting at byte location 100
Put #FileNum, 100, MyString

'close the file
Close FileNum
End Sub

You can go to http://www.vbi.org/Library/Novice/Intro/Doing%20File%20IO/Section4.html
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ahchongAuthor Commented:
yeah ~~, thanks !! but what is actually freefile, why we should use it ?
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VbmasterCommented:
The FreeFile function returns the next available filenumber (it's not used at the time anywhere else in your program). This is needed because if you try to open two files with the same filenumber at the same time you will get a error. But all this is probably already stated in the helpfile...
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dtselvaCommented:
there's 2 types of mode that can be used to open a file.
1. Sequential
2. Binary

When u open a sequential file, the data is read line by line. Meaning, no fixed length and thus, you can't move the file pointer to anywhere in the file but when it comes to binary format, it's something like a database, the length of each record is fixed thus u can pinpoint the exact location of the file but when you open this file with a Notepad.
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RuchiCommented:
The FreeFile function returns the next available file number value. For example, if you have used #1 and #2 for open files, the next value returned from FreeFile () will be 3. FreeFile () is most helpful when you write the procedures that need to open files, and the procedures may be called from more than one place in an appolication. Now matter how many files are open, the procedure will always use the next file number ... to open its file.

If you want to put the #1
Open "Test.txt" For Binary As #1

That FileNumber (#1, #2, #3, ...) represents a number from 1 to 255 and assocaites the open file with that number. If you open and close multiple files throughout the application, using that #1 might not be a good idea.

Hope this helps you a lot?
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RuchiCommented:
Oops.. Now matter how -- No matter how. :)
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wsh2Commented:
As dtselva is new to EE.. I very graciously extend our welcome. I also would like to point out, that most experts here use the answer button very frugally, and then only when they are absolutely certain that their response could be the ONLY possible answer. dtselva, I think you will soon find, that if your answer is most appropriate to the questioners need, you will almost always receive the exert points your comment merits. Once again, welcome aboard dtselva.. I think you will enjoy your time immensely.. and if you can.. try and go lightly on the answer button.. and heavy on the comment button (as most experts do).. until you become more comfortable.. <smile>.


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RuchiCommented:
Are you satisfied with the comments posted by us? See "Accept as answer" button at the right of the Comment.
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