Validate Algebraic Equations - "validating An Equation Type By It's Current Form"
Nov 5, 2011
At the moment I'm in the process of building a class that can handle more advanced mathematical equations and processes. Essentially my end goal is to to have my class capable of processing anything you'd learn in Elementary Algebra through College Algebra. So far I am able to multiply monomials and order polynomials.. However for the most part the equations in questioned being processed have to be in correct form. IE Point-Slope Form, Y-Intercept Form, etc etc. I'm just curious as to how I can go about "validating an equation type by it's current form".
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Jun 19, 2009
I store a formula in the database such as the following:GrossIncome+(Overtime/0.5)-Deductions=BasicNetIncome
I am able to substitute the string representations with actually values entered, thus:1000+(150*0.5)-100=BasicNetIncome
Then I remove the '=BasicNetIncome', thus:
1000+(150*0.5)-100
How can evaluate the above equation to return a result:
[Code]...
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Nov 5, 2009
algebratic tecniques in VB, that don't work
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Mar 30, 2011
I am looking for a way to simplify algebraic expressions in VB.NET. It is preferred if you can give me a link to a pre-written library or class.
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Mar 21, 2011
I have developed a task Using VB.net (windows Application). I want to create a Login window for the Current user only allowed to use my application.So In my Login window UserNAme textbox I have showed the curent Login UserNAme like,
txtUserName.Text=Environment.UserDomainName & "" & Environment.UserName
And I have set txtUserName.Readonly =True.
Now the User to type the Password in my application password textbox.
[code]......
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Jun 4, 2011
I am using validating procedures to validate user input from 4 text boxes. I am experiencing an issue using the 'x' button to close my form if invalid or no data is present in the textbox with focus when I click the 'x' button. Validating triggers and the message box appears. You can change the data to something valid and close fine but this is aggrevating. I changed the forms causevalidation attribute to false and created a sub to handle formclosing. In that sub I specified that causevalidation for all textboxes be disabled and also set e cancel to false. After that I tested with bad data and the message box showed again, but when I closed it the form closed also.
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Dec 5, 2005
i have a form hold some textboxes ,writed validating-event code and sometime set cancel=true in validatingnow,the problem is,when i click the close button of the form,the validating-event fired,and the form can't close when the validating set cancel=true,but this not i want.i think click "close" that meaning abandon all the form's data,so it not need validate.how can i do ?
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Jul 1, 2009
We have a window that has a text box on it that the user must enter in valid data before going on. So we have put in a message box letting the user know that they have to enter in the correct data before going on in the Leave event. That works just fine, but when the user press ALT+F4, or presses the X in the upper right corner of the window it still goes through the event. We would not like for that to happen. When we were using VB6 the same code was in the lost focus, and when the user pressed ALT+F4, and the X the LostFocus event did not fire, or acted like it did not fire. We have also tried moving the code to the Validating event, but it behaives similar to the Leave event? how to close a window, and either have the Leave, LostFocus, and Validating events not fire when the user Presses ALT+F4, or the X
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Feb 5, 2010
Is there a way to prevent the form closing event from executing if validation fails on a control? If validation on a control fails this stops the form from closing, but the closing event still executes. Scenario is user has focus in a text box, tries to close the form. Validation fails, but closing event is fired. I'm not sure how I can abort that event.
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Jun 20, 2011
For example, is this an acceptable way of checking that fields are not empty before submitting data to a datatable/database? Right now, Im simply checking with an If statement, and I'm starting to think that this is not the correct way to do it.
I'm also trying to learn more about unit testing, so if you have any tips or tricks, please feel free to share.
[Code]...
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May 9, 2012
I am writing below code for validating compulsary field account no. in form.User's requirement is set focus back on field when error comes :
If txtAccountNo = "" Then
MessageBox.Show("Account no filed can't be left empty")
txtAccountNo.SetFocus
Exit Sub
End If
It's working properly. But suppose user don't want to fill form and exiting from application.Message box keep on appearing till user enters account no.
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Jan 19, 2010
In my .NET porject, I have to run a lot of validation on 4/5 fields. This validation checks if certain fields have errors, for example: the name field is not allowed to have numbers or symbols. If all these checks are passed, I need to execute a SQL query to pull some data out of the database. I could have it with a lot of nested IFs, and run the function at the end once it passes them all, but this will translate into about 12 nested IFs, and it seems a really bulky way to do it. I have also thought about setting a boolean value after every check, and if the value is 1 then don't run the function, else do. But of course this gets overwritten by other checks that pass.
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Sep 14, 2011
[Code]...
Take a look at the snippet above. On the third line, I'm trying to set a multidimensional array to the type that the current class is. How can I get the type of the class that I am currently in? I'm using VB.net so all .net examples are acceptable.
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Apr 26, 2012
I'm trying to figure out a way to validate the user data entered:
[Code]...
This is in MVC3, VB.net. I'm looking for an easy way to validate a users input data into the editorfor field.
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Feb 28, 2012
I am trying to open a project in Visual Studio. I have VB.NET and C# installed. When I open the solution, it says
"The project file D:MyProjectsComboSample.csproj can not be be opened."
"The project type is not supported by current installation"
What do I need to install? C# is already there.
ComboSample.csproj
Microsoft Visual Studio Solution File, Format Version 10.00
# Visual Studio 2008
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ComboBoxSample1", "ComboBoxSample1ComboBoxSample1.csproj", "{6A1F1EE5-4AED-40E0-9517-3EAC47442628}"
EndProject
[Code]...
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Nov 13, 2010
I am trying to make a program to calculate the roots of a polynomial equation using the bisection method. I have designed the program so the user input a range of x values (x1 and x2) to solve for the root. When I debug the program I keep getting zero for the root. I know there must be something wrong the way I have my loop setup that keeps giving me a zero root. Here is what I have so far
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim x1 As Double
Dim x2 As Double
[code]....
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Oct 25, 2011
I'm working on a calculator. So far I've made it so you can type in an equation with as many numbers as you want like 5+6-12*3/4 and it can solve it. My main problem now though is that it's solving the problem left to right instead of using PEMDAS. For example 2+6*2 should = 14 but when I type it in it will give me 16. My calculator isn't using parenthesis or exponents so I just want to put the multiplication, division, addition and subtraction in order when solving.Could a more experienced coder give me some pseudocode to make this possible please? So far for the calc I've been using regex a lot. Is there a way to achieve this without regex?
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Mar 16, 2010
Traditionally, class/type name is literally spelled inside its definition.
Public Class MyCustomClass
Public child As MyCustomClass
Public Shared Function Clone(ByVal original As MyCustomClass) As MyCustomClass
End Class
This is not a problem most of the time; C-languages even use class name as constructor methods' name. But consider a generic declaration:
Public Class MyListOfIntegers
Inherits MyCustomList(Of Integer)
End Class
[code]....
This scenario has 2 issues. The first one is that constructors are not inherited, and you have to provide pass-through wrappers in every derived class, — this is quiet dumb, but tolerable. The second issue is more severe: derived class inherits CloneMe() method which returns MyCustomList(Of Integer) , not MyListOfIntegers ! Every returned value must be manually DirectCast 'ed for further use with methods that expect MyListOfIntegers . This issue, together with the first one, renders inheritance of generic class almost useless.
So I need a "MyClass" alternative for static type-binding inside type definition. In case of generic type that is referencing other compound types, task could be accomplished by adding second parameter to type section:
Public Class MyCustomList(Of T, TList)
...
Public Function CloneMe() As TList
[code]....
But since we must reference our own type, it would create an infinite recursive loop of additional typeparamlist arguments. How can this be resolved, aside of creating separate classes without generics?
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Jun 30, 2009
A number like 1,000,000.33 is written in another country as 1.000.000,33
which computer setting do I need to read to understand which type of number annotation is used on the current computer?
is there a way to convert those numbers in a neutral way??
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Apr 21, 2012
I have to calculate values of several equations in an application. For example, one these equations could be:
d = a + b*z + c*z (this is what is being displayed to the user, assume that 'a', 'b' and 'c' are provided as textboxes, assume that z is a hardcoded value for now)
Now, the user could enter a=1.5, b= -0.5 and c = -0.6 (or even 'a' could be negative). So, I just tried a sample code for simple values but to no avail...
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
Dim val1, val2, val3_calculated, first, second As String
first = "8"
second = "3"
Dim arr(10) As String
[Code] .....
Error:
But it throws an error saying that I am not using any databind control.
Concerns:
First of all, is it necessary to use this "eval" operator in here? Is there any way to keep "-0.5" with the sign in asp.net using vb?
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Feb 22, 2011
Actually I am trying to get a function to validate all the textboxes in my form. At the moment, my code look like:
Private Sub Textbox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Textbox1.textchanged
If Textbox1.Text.Length = 0 Then
MsgBox("TextBox1 is empty. Please enter something", msgboxstyle.okonly)
Textbox1.Focus()
Endif
End Sub
I have to write the same line of code for each textbox to check if it is not empty and was thinking of using a function that will be called and check each textbox in my form.
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Feb 16, 2011
I have set it up to email me should someone submit this form and an error occur and right now should that occur for most integer or datetime fields if they fail to validate then it will show me which fields in the email failed and what was input into them.
Problem I'm having now is to validate the drop downs and the textboxs in a similar way to what I with integer and datetime fields so I can display those also in the email in case they error.
present integer and datetime validation
[Code].....
Summary:- Need vb code to validate if strings and dropdowns are valid and the use of try/catch block is another possible solution but I wasn't able to figure out how to implement validation for that either.
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Apr 26, 2009
I am working on an assignment for Visual Basic, trying to write a program that will enable a user to enter a number and have it display that number and show in a listbox how it would multiply with numbers 1 through 12. An example of this is:
5 X 1 = 5
5 X 2 = 10
...
[code]......
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Jun 16, 2009
Is there a way to create new mathematical equations at runtime? Obviously you can pass new variables to a given equation, but I need to make a new equation altogether (then give it variables).
[Code]...
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Feb 3, 2010
Similar to using VAL(a$) to return the numerical value of a string, is there a function for returning the solution of an equation that is user-typed into a textbox? For instance, user types F$=(a+b*x)/(c*x^2-d*x^3) where the variables of the equation are either pulled from a textbox or derived within the code. I am looking for something like F=Solve(F$).
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Dec 1, 2010
The form has First Name, Last Name, Course and Email text box fields. First/Last Name must have no spaces, Course must consist of a three letters and two numbers in that order and nothing else(I want to avoid the use of masked text box), and Email must have the "@" sign and a dot. How would one make it so after clicking, say, Submit button and if there was a violation of any of the above rules then message box should pop up and tell the user which fields contain incorrect information.
Private Sub buttonAddNewStudent_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonAddNewStudent.Click
'validation must be performed before the corresponding text box items will be placed inside an array
[Code]....
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Oct 20, 2011
I have a windows form that takes username and password. It validates it with the database I have created that contains the correct usernames and passwords. So I have implemented a code to verify whether the details entered are proper..[code]
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Jun 16, 2011
I found a great way to get the equations of calculations from application to Microsoft word file with MimeTex here-[URL]
But unfortunelly the code is only for Microsoft Visual Studio Solution under the Eq2ImgWinForms folder, but I use on my application Visual Basic language (Visual Basic 2008 Express Edition).
how could I use the same thing on my application with Visual Basic?
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Oct 28, 2009
I need a VB.NET program to solve linear system with any number of equations
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Aug 8, 2009
How to validate all empty text box in a form on button click? If text box empty change color.
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