Created Structure
opened file using FileOpen(1, "filename.dat", OpenMode.Random, , , bytes in structure)
used structure .ID = record number
FilePut(1, structure)
FileClose(1)
The program enters the first record but although when I enter more records it still shows only one record in the file.
I need an example of how to create and use a random access file
View 3 RepliesI am writing a program to calculate Pi to several hundred billion decimal places and this will require lots of GB of memory. I wrote a test program in VB2008 that saved the first 16 digits of Pi (without the decimal point) to both a text file and a random access file, just to be sure it was outputting the numbers properly. For reference the first 16 digits of Pi are:
View 8 RepliesYears ago when coding with VB6 and earlier, I used a file open command to create, read, and write a file that made it easy to store useful information.I believe it was binary and you wrote/read the data to a specific line in the file. When you opened the file with something like notepad, it just showed random ascii chars. When I needed a line of data, I could specify what line to load it from.
View 2 RepliesI have some really sloppy code that creates an XML file with a random name. The random name (SessionID) is passed into the Sub, but the sub checks IF File.Exists first. If it does exist, it creates a new randoms file name based on System.Random (has to be done this way because it is also a SessionID).
View 4 RepliesI am moving all of the prgrams that I have written, to VS2008. However, I use Random Access File Foemat for the databases that have been used for over a decade. I need to be able to read and write to a Random access file.I have multiple fields in the database and cannot lose access to this information.VS2008 doesn't use the following type of code to define the Fields that will be used in the Database. I did what it suggested, using the Structure / End Structure, but that was as close to a solution that I could find in the Help Files.
Type EquipType
EquipName As String * 32
Location As String * 28[code].......
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
FileNum = FreeFile()
[Code].....
I'm doing a Program for a Friend of mine, He Want to have a Console Program Running on his Computer.OK the problem i am having is With Stream Read, I have 3 test users inside Test File, if User 1 logs in his information is store in logged file with time and data.but if User 3 logs on user 1 2 and 3 are all saved on the logged file
i dont have read to end of file in my Code.i dont have my Program with me, so i going off the top of my head i have something like this what i want to be able to find out how to do is Right from any part of the file and out put it, I take it i need to use Random Access but how to i code Random Access for this type of file. All i can find is how to Randomly place Words in a text file with Length and size.
[Code]...
I achieved reading and writing data to a random access file, buthow do I write and read data from a certain position in the *.txtfile? Would it be better if I created multiple file modes to
View 2 RepliesI am using Visual Basic 2009 to create a file of records to store students tests scores.Currently i can write to the file, create new records etc. However i cannot edit a particular record, im sure i have to use file seek function but i have no idea where to start.here is some of my source code to give you an idea of where im at
Do While (Not EOF(1)) And found = False 'loop until no more records or the record is found
nosrecords = nosrecords + 1
FileGet(1, onestudent, nosrecords)[code].....
how to read and write random access records in .NET. Now I know random access files are dead and the response on every query I found with google/bing/yahoo searches was don't use random access use Binary serialization but I can not. I have a situation where I need to read and modify 256 byte records in a file that is used by another application.
Now for a bit of background the file is made up of 27 fixed length records of 256 bytes. Each of the records has a separate structure consisting of 30-120 fields. The proplem I am having is I can create the record structures but when using the FileGet method I am receiving an error. Now I have found samples that showed the same format I am using that claim to work.
The error I am getting is Option Strict On disallows narrowing from type 'System.ValueType' to type 'ProgramName.ModuleName.Record' in copying the value of 'ByRef' paramater 'Value' back to the matching argument.
The basic layout (simplified) is as follows:
Code:
Structure Record
<VBFixedString(6)> Public SomeParam as String
Public SomeNumber as Short
[Code]....
Now the overloads for FileGet show all of the data types including Object. But I have tried various methods to retreive the 256 byte record but without success. Do I have to actually read each of the several hundred fields of the structure one by one? Or am i overlooking something (I have been known for this in the past)
Or (and I'll kick myself if this is the only way) do I just have to set option strict Off in the module and the code as above will actually work.
I would love to be able to just ditch the random access file but I have to keep it for compatibility with several other applications at this time.
The application reads information similar to a DXF file. For purposes of discussion, the data consists of lines, those lines have endpoints, x1,y1,x2,y2. Within the file those lines create "paths", in other words, they are connected. There can be many separate paths within a single file. However in the original file, the geometry is not in any particular order, the paths are not indicated.
View 3 RepliesI'm tasked with the job of creating a javascript version of a units conversion application written in vb6. I have the source code but I don't have vb 6. The source code uses a dat file to hold a conversion array (unit type, unit, xfactor, plusfactor). Getting the data out of this file would be good to me. I tried creating a little app in vb 2010 to write the data from that dat file to a txt file using essentially the same code as the source code. And that has been somewhat successful (took a while to figure out the fixed string business). Now I can pull the data out as an array. The math elements of this array look fine but the strings are somewhat read-able but too garbled to use. I can't seem to fix that by changing the character set/encoding.
View 3 RepliesThis time, basically, i'm working with Random Access Files.I have this et of code to read data from a form a save it into a .dat file. This works fine.
Public Class frmDramaClub
Structure MemberRecord
Dim ID As Integer[code].....
how to proceed. One of our customers is going to be sending me a flat file (ASCII-Text) that I have to break down and scan. Every line ends in a CrLf - So I know I can use StreamReader and ReadLine(). I did get it to work on one of the test files they sent.(A very Short file) However, the file is not delimited at all and every field is padded to the full length they specified. Here's the format of the file:
[Code]....
I have a flat file that is sorted by account number. I am migrating an application that was in vb6 to .Net. The application uses Random file access and uses a binary sort method to find a record.
Here is the code
Do While (low < high Or low = high) And (f = 0) 'Checking for an account match
middle = (low + high) / 2
FileGet(FileNum, Record, middle)
If Account < Trim(Mid(Record.Data, Byte1Start, Byte1Len)) Then
[Code] .....
From reading up on this in .Net it seems that using the Binary Reader seek method would be the alternative to using old vb6 random access code. The problem is the Binary Reader Seek method goes by Byte position instead of record number. How to convert my code to use a binary reader.
When you need to do random access to the lines of a text file, the regular solution is to put those lines in a list and access them in that list.But doing this if the text file is large creates a large memory overhead and may cause some memory stress on the application.This class maps the file and provide the ability to read any particular line in the file at a random position, without the need to read or put in memory any other line but the desired line. The only memory overhead involve is the 1024 bytes buffer of the base stream.Even if the file mapping can be a process that consume a noticable amount of time if the file is very large ( ~ 5 seconds for each 100,000,000 caracteres) , once the mapping is done the access to a particular line becomes instantaneous regardless of the size of the file. (The file mapping can always be done at a convenient time (ex when the process load) and can be done on a worker thread The class is base on a StreamReader to support the differents Text Encodings Example uf usage ( As I say, if the file is very large, dont do it like that, but declare the class at a convenient time)
Imports Reader = System.IO.MyStreams
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code]....
Using VB I can create and access a random "cell" in an array like so
[Code]....
Is it possible to create an ms access file, create some tables with certain properties, and then change its extension and associate it to my application using VB.Net?
View 1 Repliesi not sure can it be done.
Using VB.net by typing the name and hit the button to Show the person record from the database access.
the log file will pop out and show the person record in VB.Net
is it possible to create a MS ACCESS file with click of a button. (what if the client pc doesn't have MS Office install only ACCESS run time is installed.if yes what will be the code to create a file let say c:/1.accdb
View 1 RepliesI tired this [code]...
but this code not working on windows vista, i can use it on windows xp, i think problem is user permissions but i have to delete or create file via my application how can resolve this problem.
i need to access file names so i can change them using my program. i need to also have a browse button which brings up a box to navigate and select a folder which i can then change the name of all the pictures within it.i have a text box which i will use to replace the existing name with a name that i choose such as 'dnjnjnf' change to #1, #2, #3 ... ect so will need a loop to increase the number everytime.
View 7 RepliesI wont to be able to check if a table exist, if not i wont to create it...
This is the code i use for connecting...
Code Block
Im trying to write to a file I created and place "Unregistered" in it. Thought it would be a simple task but keep getting an error. Its happening when I try and open the file to write. This is the error: Access to the path 'G:\Projects\Project\pbss\bin\Debug\5\pbssv\Data.DB' is denied.
Ive tried adding the file attributes to read-write and still get the same. Most of the code ive looked at via a google search points to the same as ive got for the Added default value area. Im not sure if there is a conflict between the 2 different ways im accessing the file when creating and writing too? [Code]
An OLE Object column contains images but the image type (jpg/gif/tiff) is unknown. These images need to be extracted from the DB and saved to disk. The application is primarily using VB.NET but C# examples are welcome too.
View 3 Replies1. I have to create a file. 2. Then I want to write a string into the text file.
I can do part 1 no problem with: File.Create(strFilePath) But when I try part 2 to write to the file it won't allow this as it's still being used:
sw = File.AppendText(strFileName)
sw.WriteLine(strCode)
sw.Flush()
sw.Close()
My code in part 2 works fine on a file that hasn't just been created.
How do I release the file from the File object?
There doesn't seem to be a .close or .flush option.
I wrote an application which parses a website and downloads an mp4 file from website. User can select the path where he wants to download the video. When I try to download I get an exception for the file, Access Denied to Path. When I gave the permissions to folder that I chose, then works fine. How can I resolve that problem? End-User will select the folder. How do I change the permissions?
View 1 Repliesmy form is connection to an access db ....called Quiz.db , it has 10,000 questions and answers , i want to click button and generate random question with correct answer , so ID# of record must be random on load and click next?
View 3 Repliesi have errors while creating
View 13 Replies