.net - Dealing With Large Integers?
Apr 19, 2012
So I am making a file crypter so that I can encrypt my VB.NET Application that I am making so that people can't decompile it. I had made this in C# and am transfering it to VB.NET, Everything worked fine in C# but once I had re-written the code in VB.NET i get this error inside of my RC4 Encryption method:
'Arithmetic operation resulted in an overflow.'
The error is occuring here:
Dim t As Int64 = (s(i) + s(j)) Mod 256
This is the same code above in c#:
int t = (s[i] + s[j]) % 256;
Is there anyway to make that calculation with it erroring? And why does it work in C# but not VB.NET?
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Sep 20, 2010
I am using a stored procedure to fill a dataset with a large amount of data (47k rows and 8 columns). I am needing to fill two tables with the results of this stored proc.One table will have data representing 47k reps that currently have credit for a transaction. The other table will be a mirror copy of the 1st table with 47k reps that were supposed to get credit for a transaction. This application is going to take credit from one rep. and give the credit to the other rep record in the 2 mirrored datasets. It's taking 30 seconds for the data adapter fill method to return records to my application. I would like to reduce the amount of time it takes for this request to process.
[Code]...
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Mar 12, 2012
I want a method of dealing with very, very, very big numbers (potentially a million digits). It is very cumbersome to deal with very big numbers in VB, would another language perhaps be better for that?
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May 21, 2009
I am making an inventory program in which there's an ItemMaster and Sales Form. Currently there are 15000 records of items(increasing daily). I want to display all the items in the sales form so that the user can select an item from the list for billing, and also in the itemmaster so that if the user wants to edit any item then he can select it from the list.
I can make a common list form for both sales and master, but i have to load the data from the database into the list every time the list is displayed(which is taking lot of time), so is there an better way to do it.
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May 5, 2011
I have a bunch of 10 digit integers that I'm passing in a URL. Something like: "4294965286", "2292964213". They will always be positive and always be 10 digits. I'd like to compress those integers into the smallest possible form that can still be used in in a URL (aka letters and numbers are perfectly fine) and then uncompress them later. I've looked at using gzipstream but it creates larger strings, not shorter.
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Mar 20, 2010
I tried coding for an application that will display the positive integers, negative integers and zero entered in a inputBox. for some reason it keeps crashing down.here is my code. paging all visual basic professionals. [code]
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Feb 2, 2012
Basically I have and array of integers that vary in size. I need to compare each number to each other number and display which number is repeated. For example:
Dim ints() As Integer = {1,2,2,5,4,6}
The number that shows up more than once is 2.
How can I run through the array and compare each integer with the numbers in the array. I tried a for loop but it didn't return the value I was looking for.
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Jun 9, 2011
I want to write a program to do Markov chain, but my states are quite large. First of all I calculate all the transition probabilities and revenues for all states(1381860 total states), and store in a multidimensional array. Public RevArr(0 To 9, 0 To 750, 0 To 282) As Long
After that the iteration of markov chain should use these as inputs to calculate the steady-state probabilities. But when I try to run the main code I got this error.Exception of type 'System.OutOfMemoryException' was thrown.
The following is the declaration of second array I add just another dimension for storing all the iterations, but I get this error. Dim stateprob(IT + 1, 0 To 9, 0 To 750, 0 To 282) As single
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Jul 5, 2009
I recently found myself in a thread deling with convertions from decimal number to fractions... Being a bit too brusk and dismissing the idea at first.I have now implemented a structure based on code frm Javelia whithc can be seen in this thread.Solitare also proveided code that I eventually understood and was working.[URL]...it a step longer and developed a structure that can also implement calculating with fractions... My first try is also posted in the tread above...
The implimentation is far from perfect, as it does not deal with POW of fractions.. So if anybody has some ideas on hoe to do this with squer root and all pleas let me know and Ill update the code..
[Code]...
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Jan 6, 2012
I have a function called Modify. It is delcared like so:Public Function Modify(Of SIMType As {New, DAOBase})(ByVal obj As DAOBase) As Boolean
You can see that this function is generic. It takes as a paramer a object that is a DAOBase or subclasses of DAOBase.Inside the modify function there is a call like so:
DAOToGP(obj)This is where the polymorphism comes into play. There are four or so subclasses I have created of DAOBase. I have written a DAOToGP() for each of these types. So in the Modify() function, when it calls the DAOToGP(obj), polymorphism should kick in and it should call the correct implementation of DAOToGP() depending on the type that I pass into Modify().
However, I get the following error:Error 20 Overload resolution failed because no accessible 'DAOToGP' can be called without a narrowing conversion:'Public Shared Function DAOToGP(distributor As Distributors) As Microsoft.Dynamics.GP.Vendor': Argument matching parameter 'distributor' narrows from 'SierraLib.DAOBase' to 'IMS.Distributors'.'Public Shared Function DAOToGP(product As Products) As Microsoft.Dynamics.GP.SalesItem': Argument matching parameter 'product' narrows from 'SierraLib.DAOBase' to 'IMS.Products'. C:Usersdvargo.SIERRAWOWIRESDocumentsVisual Studio 2010ProjectsSIMDev_2SIMIMSDVSIMLibGPGPSIMRunnerRunnersRunnerBase.vb 66 39 IMS
I am kind of at a loss here. I am not sure why it cant figure out which function to call.
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Aug 23, 2011
my code works fine in JavaScript but doesn't work correctly in Firefox or safari and wondering why. What I'm doing is I have a loop going through each element and depending on the variable inside a text box just want to alert something. Like i said earlier this code works fine in IE. Here is the code below:
Here is an example of text box:
<asp:TextBox ID="txtMac" runat="server" req="yes" errMessage="Mac"/>
for (a = 0; a < theForm.elements.length; a++) {
if (theForm.elements[a].type == "text" && theForm.elements[a].req == "yes") {
alert("Made it here")
}
}
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Jul 19, 2011
Problem dealing with apostrophe in filter?
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Sep 21, 2009
I've been messing around with prime numbers for a while now, but I now want to use massive numbers, say a few million digits in length. Is there a way of storing and performing mathematical functions with such large numbers? Is it even possible on my home computer? I read on another old thread, something about a big number library, but the links he gave are now dead.
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Jul 30, 2009
I have a website and say a user comes along and fills out the form with bogus data. Then after he fills it out, he enters another one and another one and another one of bogus data. He's basically just trying to clog up the data base.
How is the best way to combat this? Would it make sense to when they submit the data track the IP address?
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Jan 6, 2010
I sure this has been asked more then once... New to vb.net and I have been experimenting with a datetimepicker and how it looks at and deals with time. What I am trying to do is to add up my time (not worried about the date at all). I have it figured out and can get it to work so long as I do not go over 24 hours... and that is where my issue comes into play.
How do I display my total time in hours once it has gotten over 24 hours ( I do not want days.. just hours) for instance, a 40 hour work week, not 1 day and 16 hours.
[Code]...
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Jun 10, 2009
A partner of ours is making a call to a web service that includes a parameter called token. Token is the result of an MD5 hash of two numbers, and helps us authenticate that the user using our partners system. Our partner asks the user for two strings, concatenates them, runs them through MD5, and then calls our web service. The result of the MD5 is the token, and it is submitted to us as a string.
We store valid tokens in a DB - since we use the SQL Server to compute the tokens on our end, SQL seemed to be happiest storing the tokens as a varbinary, which is its native result for an MD5 computation.
We have two pieces of code that attempt to do the same thing - run a select query that pulls out a value based on the token submitted. One uses a dynamic query (which is a problem), but it works. The other one attempts to do the same thing in a parameterized (safer) fashion, it does not work - it is unable to locate the token.
Here's the two competing attempts. First, the parameterized version which fails:
byteArrayToken = System.Text.UnicodeEncoding.Unicode.GetBytes(stringToken)
scSelectThing.CommandText = "select thing from tokenstable where token=@token"
Dim param As SqlParameter = scSelectThing.Parameters.Add("@token",
[Code].....
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Feb 9, 2010
Some tables I am dealing with have null values and are throwing errors. So far ive tried a few solutions to deal with the nulls with no success.Here are the code samples from my efforts so far;
If (r("datemodified").Equals(DBNull.Value)) Then
datemodified = String.Empty
Else[code]....
i have ran the query and it is working ok (i.e all the cols exist)
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Jan 12, 2012
Dim myreader As SqlDataReader = cmd.ExecuteReader
'read information from the database and give the values to the arguments(column_1, and column_2)
While myreader.Read
column_1 = myreader.GetString(1)
column_2 = myreader.GetString(2)
.....
I get an error when the data returned from myreader.GetString(2) is NULL. How do I check for nulls before assigning column_2 a value?
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Aug 3, 2009
I'm trying to test a varbinary(max) field to see if it's null. I'm trying to figure out if it's a null or not in the select statement, hoping to avoid having to do this locally for every row of the returned dataset. This is the SQL I'm using,
[Code]....
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Feb 1, 2010
Is there any way to convert null terminated string to normal string.I mean I can easily make a program to find the location of vbnull but there has to be a built in function for that.
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Jul 8, 2010
Some tables I am dealing with have null values and are throwing errors. So far ive tried a few solutions to deal with the nulls with no success.
Here are the code samples from my efforts so far;
If (r("datemodified").Equals(DBNull.Value)) Then
datemodified = String.Empty
[code].....
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Nov 20, 2009
Is it possible to translate the following C# code into VB.NET, using VB 9.0?
delegate Stream StreamOpenerDelegate(String name);
void Exec1()
{
WorkMethod( x => File.OpenRead(x));
[CODE]...
Can I do something like this?:
Private Delegate Function StreamOpenerDelegate(ByVal name As String) As Stream
Private Sub WorkMethod(ByVal d As StreamOpenerDelegate)
''
End Sub
[CODE]...
I'm trying to write some documentation, but I don't know VB syntax. Often I use Reflector to translate it, but I'm not sure it's working in this case. I'm also not clear on where I would need line continuation characters. In VB9, it's not possible to have multi-line lambdas (or Sub lambdas, which I did not ask about). In VB9, all lambdas return a value, and must be a single expression. This changes in VB10. VB10 will allow the above syntax, but VB9 will not. In VB9, if the logic involves multiple code lines, it must not be a lambda; you must put it into a named Function and reference it explicitly.
Like this:
Private Delegate Function StreamOpenerDelegate(ByVal name As String) As Stream
Private Sub WorkMethod(ByVal d As StreamOpenerDelegate)
''
End Sub
[CODE]...
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Oct 24, 2009
1. I having a project dealing with MsAccess database.
2. Currently the project connect the db using table adapter/data adapter method.
3. When I called a Me.SubjectCourseTableAdapter.Fill(Me.ProgrammingDataSet.Subject_Course) at frmCourse, it return me error message "System. NullReferenceException was unhandled Message="Object reference not set to an instance of an object.""
4. This line of code is just the same at frmA. Wonder why it will cause error at frmB.Besides, which is the better way to connect access? data adapter or ado.net?
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Jan 14, 2010
I have a main form which contains a few buttons...some of those buttons open up smaller forms...there is also a button for each of those smaller forms, which should let me bring the chosen form to the front and give it focus...basically like the tabs in your task bar let you switch between which program you are using...but I'm having trouble with this...I need to click the button 2 times before the form I want comes to the front...the first click removes focus from the currently activated form the second click then moves the form I want to the front.I need this to happen in one click..I[code] figured out the exact cause of the problem.it's due to the fact that the first click doesn't actually take effect since the child form has focus...so the first click actually just transfers focus to the main form...the second click does what it should.I knew it was going to be extremely obvious.so the question now becomes...how can I overcome this if that is possible at all...I know I've seen applications where I can still activate functions of the parent form in one click even if I have a child form open and focused.And it's basically what I need...it does what I want and lets me switch between child forms in one click...but it stuffs up the entire look of my parent form...the layout and colors get wacky...the transparency of certain things don't seem to work and my background image is gone..
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Jan 30, 2012
Suppose I have two events:
Public Sub Control1Updated() Handles control1.TextChanged
control2.Text = SomeFunction(control1.Text)
End Sub
[code]....
Basically the pairs of {control1.Text, control2.Text} and {control2.Text, control1.Text} should be the same. If control1.Text is changed to let's say "a" then control2.Text is ALWAYS "b". If control2.Text is changed to "b" then control1.Text is ALWAYS "a". How do I achieve this with events without going into an infinite loop? [the best I can think of is to make a check if the other control.Text is already the desired value].
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Jul 28, 2010
Does anyone else wrestle with getting VB.NET Linq code formatted the way they want it in Visual Studio? What are some tricks you have for how do you deal with it? I know that Visual Studio lets you uncheck the option for "Pretty listing (reformatting) of code", but most of the time it's a really handy setting to keep on. And with a team of developers who could have other settings, that's not really a viable solution. So my questions are:How have you dealt with formatting multiline Linq statements in VB without fighting with Visual Studio's code formatting?Is there a particular style guide for Linq in VB.NET that is recommended? Something that is readable, and that Visual Studio likes without the reformatting nightmares? My original question may not have had the clarity I desired. Here's a more concrete example. [code]
Everything is all nicely formatted and lined up, but any changes to the query result in Visual Studio borking the formatting and only an immediate CTRL-Z will stop it. Which is fine if there's a standard way that VS would like to see multiline Linq formatted, but if not, then the constant reformatting VS tries makes no sense. I'm trying to see if I missed some standard or how others in the community deal with this effectively. (BTW - using tabs instead of spaces for indents.
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Apr 7, 2009
I'm using VB.NET 2005 trying to create a options form that lets you select the serial port to use I'm using:
HTML Code:
Sub GetSerialPortNames()
' Show all available COM ports.
For Each sp As String In My.Computer.Ports.SerialPortNames
Serial_list.Items.Add(sp)
Next
End Sub
To create a list of ports this works then using
[Code] .....
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Oct 3, 2010
I addressed a meeting and used the following....she worked there for 17 years.I was corrected later that it should have been 16 years.I argued that the first year of this persons employment was 1966 and her last years work was 1982. Therefore 17 years.Does someone have an articulate mathmatic reasoning that explains dealing with inclusive numbers.
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Sep 30, 2011
So I did tons and tons of work trying to make an interface for a common set of classes. The idea was to make an interface that each class could use within the set, but ultimately each class is different. Turns out interfaces do not like shared members. What I tried:
Public Interface ISomeInterface
Shared Property Meta() as Object
End Interface
Public Class A
Implements ISomeInterface
[Code]...
Obviously, had I done my homework on this, I would have known that shared members can't be use in interfaces. Should I just leave the individual classes completely responsible for handling its shared members? Is there another way to keep coupling down to a minimum with shared members? Theres about 20 something or so classes that will implement a single interface.
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Jan 1, 2012
I am looping thorugh a datatable and and printing each row to the console and I keep on getting a dbnull error. I inserted an if statement in my loop to try and catch it, but I can't seem to get it to work.
[Code]...
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