Recently I experiment with the binary file type. I have this structure[code]...
It works. And now, in the load event of the form I want to know, how many records (structures) are stored in the file.
Another question: how can I search and seek in the file (structure to structure, not byte to byte)?
I need to write data to a file, preferably in binary format, but I am unaccustomed with the concept. Where's the easiest place to get the basics? I could come here with a specific need, but I'm at the point right now where I am more willing to work within the confines of keeping it simple.
Here's what I know:
1. how to open a new file
2. how to specify the record length
3. how to close the file
Some specific questions:
Does the record length have to be constant throughout the file?
Can I read the nth record without reading the whole file?
To read a record in a binary file in VB^ I would define a type with all the fields specifying strings as STRING * whatever the length of the field was.
For example:
Type Record
Field1 as string *15
Field2 to as string * 20
Field3 as String * 10
field4 as byte(10)
End Type
Dim filerecord as record
I would the open my binary fiel and do a Get#1,, filerecord
The record would be read and all the fielsd would be in place.
Now with the new Structure we cant dimension an array in the Structure And wjhen declaring strings we can't specify the length.
I tried to create structire and use a stream binary reader. and just read afixed number of bytes into the type, The program says it canvert bytes to my fiels.
So how do I do this. Or has Microsoft in their infinite wisdom left no way to do this.
I used to read a binary file by formatting a record type and then using the Get command to get the data. What is the equivalent in VB.net?
Code:
'In Module.bas
Public Type recordtype
dist As Single
[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.
The question is quite simple for all of you . I have a binary file . A description for this file says that
[Code]...
I am creating a class that searches a binary file for a specific customer number. I am using a binary search that keeps on slicing the file in half until I find the customer number while is sorted. Once it finds it I am positioning it at the first instance of that Customer number as there can be multiple records with the same Cus Number.
Now here is my question. I now need to loop through this Customers records and do some data base searches. Since I want to make my class as generic as possible what should I pass back to the calling class? An Array with all their records. If I do this I have to loop twice, once in the class and once when it passes the array bac to the original calling class?
[Code]....
I am currently working on a flatfile based database, meaning: all database records are saved in single files in a data folder of my main application. So far everything works fine except for one thing:
Each record gets currently saved as file under its item name. This sometimes causes problems because some item names contain special characters which can't be used as a file name. What I would like is the following: Whenever I 'add a record' to my database it should be saved in a file with a 4 to 6 digit number as file name - to keep things simple I just ignore the file extension for now.
For example, I add a new record with the ITEM NAME Flower "Blue River" #1 - I won't be able to create the file because of the special characters in there! I would like that the program creates automatically a file in a 4 or 6 digit format (I haven't decided yet how many digits because I am not sure how many data records I will need one day, so, 4 digits will be enougth for now!), starting at 1000, so, the file I am creating is called 1000 + whatever extension I will give it later.
In addition, I would like that it checks for missing numbers in between when creating a 'new database record', meaning: I have already the folloing file names: 1000, 1001, 1002 and one day I delete the second record, so, 1001 would be available for the next new file / data record which I add to my database.
So far I've experimented with the GUID but the filenames I get out of it are just not in an 'eye pleasing' format. Would there be a way to give this GUID a special format or is there any other good way to accomplish that?
I want to convert numbers from 0 to 15 like that
[Code]...
Problem is that when we convert 2 to binary number it gives only 10 in binary, but i want to convert 2 to 4 bit binary number 0010.
I am trying to add a new record everytime i do my navigation gets all messed up I also need an update button... I would like so when i hit new record the record of will be(ex. If Im adding record number 30 it will say record 30 of 30, hit add new it will say record 31 of 31) my code is below.
'Class File
Module Class1
Public MasterConnection As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=db1.mdb;Persist Security Info=False;")
[code].....
I am handling many of the BindingNavigator tasks (MoveFirst, MoveNext, etc.)in code to ensure that I always ask the User to save his changes.
The one area I am have a problem is PositionItem. I would like to sense that the User has changed the Record Number in the BindingNavigatorPositionItem, handle my record Update, and move to the Record Number the User entered I have looked all over and have not found any way to do this.
For the life of me I cannot find the solution to this error. All field lengths match the length of the SQL Server data field. Here is the insert code I am using... the same to the code that is used elsewhere in the program.SQL Server Express 2008 R2 and VB 2010 SP1.
Dim blnInputError As Boolean = False
Dim blnPrimaryKeyError As Boolean = False
Dim blnIsError As Boolean = False[code].........
i'm beginer in this forum and new in vb6.how to generate random number in vb6?
is it posible to represent variable in binary?
GUI: textbox1.Text, button, textbox2.Text What i want to do is when the user inputs an 8 bit binary number The program finds the places of ones and outputs them For example: user inputs 00010011, the program outputs a 4,1,0 because the 7th place is the one closest to the left and the 0th place is the farthest, e.g. 76543210 is and in the 8bit string the 4th 1st and 0th are ones I was thinking of something like this:
[code]...
Can anyone help me to break down the instructions for this assignment.Create an application that allows the user to type in a 32 bit number using the binary system, and convert that number into the decimal numbering system.For example, the user types 000000000000 0010 (where there are 30 leading 0's, 1 then 0 from left to right), and the output would be 2.The user will type a string that is 32 characters in length.A For loop 'reads' each character using the x.substring(i,1) where i is the current character we are reading and 1 means one character only,and x is the entry the user typed (use a Textbox to get the entry but Inputbox is also ok).When you start at the first character (from the right) then that value is to be * 2 ^ 0 then the second character is to be * 2 ^ 1, then the third character is * 2 ^ 2, hence:( x.substring(i,1) converted to Integer ) * 2 ^ j represents the decimal value of the current number (0 or 1) we are reading.A variable is needed to accumulate all those values.After the loop is done, display the accumulated value.To test this code on a simple version, enter a 4 digit binary number, where 0010 is decimal 2, 0110 is decimal 6, 0111 is 7, and 1000 is 8.
My understanding is the user must enter 32 digits into a textbox. The textbox should place limitations that only allow the digits "0" and "1". This error could be displayed to the user with a messagebox that then asks to reset the value orginally inputted into the textbox. My understanding is I should continue creating the formula of the position of each character where the third character is *2^2, fourth is *2^3, fifth is *2^4 and so on? I don't understand the formula and how it works.
Im wondering how would i work with a text file. which would allow me to Read the next Record, Cut record out of the program.
View 15 Repliesi need to read binary file and in this file found the string and replace it with other one and save the file afterwords. I found many example to read binary, but to find and replace is for me mistery.
View 3 RepliesBasically, I am making a booking system. On one of the forms, you can: Add, Edit and Delete a record by using the selected index. I can do the Add and Edit part fine but some problems are occuring when I try to delete it. What I'm trying to do when deleting is, copy all the records except the selected one and then copy it back into the original file again.
[Code]...
How can i get the postion of the pointer or record number from a datagridview when a user clicks on a cell in the datagrid.?
View 4 RepliesSay I have a table called tblTest in MS Access with the primary key called field0 which is set to autonumber and a few other fields, say field1, field2 and field3. Say also, I inserted a new row using:
SqlO = "Insert into tblTest (field1, field2, field3) Values (value1, value2, value3)"
Dim cmdO As OleDbCommand = New OleDbCommand(sqlO, conn)
cmdO.ExecuteNonQuery()
[code]......
below is my code, i want to get a record base on a specif invoice number?
Imports System.Data.Sql
Imports System.Data.SqlClient
Public Class Invoice
Private Sub Invoice_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code]....
I have a data set with a table named IEA_Transaction_Test2.After executing the below codes to insert a record into the SQL server table IEA_Transaction_Test2, how do I get the identity value (auto number) of the record that just got inserted?
Me.Validate()
Me.IEA_Transaction_Test2BindingSource.EndEdit()
Me.IEA_Transaction_Test2TableAdapter.Update(Me.MyDataSet)
I have an Access table which has an auto-number primary key. When I add a new record to it I want to be able to get the value of this field.
The relevant code I have is:
dsNewRow.Item("FullName") = NewStudentFields(0)
dsNewRow.Item("FirstName") = NewStudentFields(1)
dsNewRow.Item("LastName") = NewStudentFields(2)
[Code]....
I want to be able to access the value of the primary key immediately after the Update (if that's possible without having to search the dataset for the new record - cumbersome!) or, even better, just before the Update, if that's possible.
I've gone through about 16 hours and two packs of cigarettes trying to figure this out. First a little background. I was using 6.0 up until 2004 when I went to prison. I'm out now, and trying to relearn the trade, using VS 2005. I'm currently porting some 6.0 code from another project, SpyCast Webcam Studio, into VB 8.0. It's disheartening, to say the least. None of the old built-in subs/functions work anymore, so I have to scour the forums to relearn each and every function.The section I'm doing now takes a snapshot from the webcam (Video API --> PictureBox --> Save as Jpeg), then upens the file to upload it to the server via HTTP POST. I've been using this code in SpyCast for years with no trouble, but I spent many hours trying to piece together the right code to open the binary file to read its contents. I pieced together two methods I found around the forums, one using FileStream() though the code I found wasn't for binary files, even though it said it was, so that code doesn't really work. Method two uses Microsoft.VisualBasic.FileOpen() and works better.
Here's the kicker. By the time I run through the rest of the rigamarole of uploading the file, by the time I read it on the webserver, it's *slightly* corrupted. It's a valid Jpeg, no errors, but the picture looks like when I use to watch the Playboy Channel when I was a kid scrambled with weird colors and whatnot. [code] Each "chunk" is basically one "line" of the file. It looks like a single LineInput() return is the text between two carriage returns. Am I correct? I tested this with a flat text file, and it looks true. However, That one input line returns the text or data with the carriage returns *stripped*! ***?!? =( Fine, I have no problem adding my own vbCrLf to each LineInput(), if I were opening text. but this's binary. A character could be Chr(10) or Chr(13), both of which are removed from the original file contents.So I could very well need to use something other than LineInput(), but I haven't found any other examples on the web using this method.
I am writing a parsing method for a csv record and want to throw an exception if the number of fields in the record do not match the expected length
View 3 Repliesmy table name is "temp", and one of the field is item_id..how can i count how much item_id was added in this table...??is the code "SELECT item_id, COUNT(*) FROM temp GROUP BY item_id"it doesn't work.. i'm using OLEDB connection and can't use sql property
View 8 Repliesi know the record position or number of datatable and the same table is used as datasoure to grid. i want to find out the row number in the grid for current record in datatable. in case grid is not sorted it is easy but if grid is sorted then row number change in the grid.
View 3 RepliesI am attempting to create a program that opens a file and reads the contents to then display them in a set of four text boxes (e.g. id, firstName, lastName, avg.Salary). it stores the data in an array.
i have done all that i can do, however, i wish to display in a label something similar to this "5/10 (5th record of a total of 10)" meaning the 5th record in the array out of a total of 10 records. i have already done the code to display the total amount of items in the array, that part was simple, but i can't get my head around trying to code something that will display the record that i am currently viewing in the text boxes.
i have a "view previous record" and a "view next record" button that will go through to the next or previous record, in doing so will change the "5/10" records to the next appropriate number, e.g. "5/10" goes to "4/10" if the previous button is pressed (in doing so, obviously the records that are shown in the text boxes will change to the next or previous record)[code]...
I want to display the index number of the selected record in a listview box as it is clicked by the user. I can do it with multiselect set to false and the following call.
Private
Sub ListView1_SelectedIndexChanged(ByVal
sender As System.Object,
ByVal e
As System.EventArgs)
Handles ListView1.SelectedIndexChanged
[Code]...
This works fine except for one thing! after I click OK to the msgbox prompt, the record highlights normally and I click on the next record, and I get an Argument out of range exception error message, where I expected to just get another message with the next record number.
I have a table from a database and i need to display the total number of record and display it in a label.i already have binding navigator but i will not use to display the total number of record in that table. and i will also make that binding navigator invisible.
View 2 Replies
