I've created a program that pulls item prices from a database. The problem I'm having right now is that I'd like to display a running total, as the program currently only displays the list of items and their prices.
Private Sub btnGoToCart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGoCart.Click
Me.Hide()
[Code].....
I am in the middle of building a very simple shopping cart in asp.net with a VB backend but I am running into problems with my code. When I run my application and try to add a product to the cart I get an error message.
Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
Line 27: Dim blnMatch As Boolean = False
Line 28:
Line 29: For Each Me.objDR In objDT.Rows
Line 30: If objDR("StockItemName") = Product Then
Line 31: objDR("Quantity") += txtQuantity.Text
I am not sure why it is doing this and was hoping that perhaps someone could take a look and offer up some advice? I have checked over my code and I cannot find anything wrong however I would take any guidence that you may have on it.
[Code]...
I am trying to create a shopping cart in Visual Basic. I have most of it figured out. However, when I click the Add Cart button, the item will add; however, when I add a new item, it will not go to the next line to display it. It instead replaces the first item I added. For example if the user chooses 1111 for the part number and qty is 2 then clicks the Add to Cart button, the following will show in a group box below: 1111 Alarm Clock 2 $19.95 $39.90
If the person wants to add part number 2222 and qty is 2, that relating info should show up below the first entry of the Alarm clock. In my code, it's not doing that, it's just replacing the first line (alarm clock entry). However, it is keeping track of the total amount added to the cart.
Here is my code that I have done for the Add Cart button:
Private Sub xAddButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles xAddButton.Click
Dim searchFor As String
[Code]......
I am building a shop (without payment)
i.e.
1) Select Products
2) Checkout
3) Confirmation
The selecting products screen will look like a gridview which will display.
name price quantity
Text Text Input box
So i.e. lets say I have 10 products per page so i.e. 10 quantity input boxes per gridview. And then I have 2 Buttons below my gridview i.e. Update and Checkout. Just even worrying about Update for now. How could that work i.e. would I have to check every input box in gridview for which a value was entered ?
I.e. is there any example how I can loop through gridview row check for a value which is greater than 0 or null for example and if there is a value then perform a function like [Code]
I am working on a class project and I am trying to create a shopping cart application. I need to transfer info from listboxes on 2 forms to the main form and calculate the charges for "the books." I am having a hard time writing the code to properly transfer the items and I really have no idea where to start with the calculating the charges for subtotals of the selected books.
View 3 RepliesMy project is to create a shopping cart application. I have my main form and from there the user can go to two different forms to add books to their cart, the cart being the main form. This all works. What I can't figure out, is how to use global variables for the prices, shipping, tax and updating the total. I have places for this information to show up on the main form, and I've created a module for the calculations and prices, but I don't know how to code it to get the prices to show up in the specified areas.
View 3 RepliesHow can I get the items in my code from my listbox which is called "selectListBox" to a shopping cart called "cartlistbox", when the add button is clicked?
Public Class MainForm
Private Sub MainForm_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
[Code].....
Using following method to create Shopping Cart Session [URL]Now running locally on my machine where sessionstate mode is inProc by default, all seems to perform fine.I'm writing an application which I've just placed up on hosting provider (shared hosting environment etc). Their default sessionstate is stateserver so I had to serialise the classes to fit in with this. It's using cookies.The basket (adding,removing etc) works fine but I'm seeing some odd things happen regarding the persistency of the session.
On my local machine, if I access the site in 2 separate browsers, if I add items in IE, I can see them in Firefox when I refresh. This doesn't make any sense to me since cookies are per browser.Plus I thought that when a session was generated, its id would be unique so there is no way that one user should be able to see anothers session data (unless tabbed in same browser perhaps)Even worse, if I start adding/removing items in IE and doing likewise in Firefox, both of them show very random cart results every time you refresh the browser.
Note: This code actually codes from a tutorial book I'm reading at the moment, so you can imagine this is frustrating me greatly! I'm building a basic shopping cart, using VB.NET 4, Visual Studio 2010 and MS SQL Server R2 2008. The code below is supposed to remove items from the cart, by reading a session variable, editing it to remove the appropriate ProductID and return the amending string to the session variable. It is then supposed to rebind the data to the gridview (gvCart) to refresh the data...but it seems here there is an error.
Every time I build the site in Visual Studio, it validates fine. But every time I run the site, and attempt to use the remove button it gives me the error:Incorrect syntax near ')'.ith the IDE pointing me toward the final parenthesis
Protected Sub gvCart_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles gvCart.SelectedIndexChanged
'This method is hooked to the Remove button & is removing items from the cart
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I have a gridview as follows
<asp:GridView ID="productListTable" runat="server" DataSourceID="srcProductListPerCustomer" AutoGenerateColumns="False" AlternatingRowStyle-CssClass="tr_dark" HeaderStyle-CssClass="header_req"
[Code]....
And it actually seems to work on first instance (altho im not sure the above is a good way to do it, but the problem is when use the pagination on the gridview I get the error
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
On the line
Dim productId As String = productListTable.DataKeys(i).Value
why I am getting this error and also is there a better way to do it ?
i havent had problems in visual basic all the ay up to this point. I have been given a shopping cart program that I must use: a MainForm, MP3From, AlbumForm, and a module
I finally got my program to send data from the listbox on my MP3Form to the listbox on my MainForm but something isnt right still. I need to be able to click an an item from the lstMP3(listbox on MP3Form) to lstShoppingCart(listbox on MainForm) multiple times without having to close the MP3Form everytime to add the items to lstShoppingCart. Here is what I got so far on my MainForm:
[code...]
This assignment makes me mad cause we have not even covered half the stuff I am having to use in this form at all this semester. If i can get a little explanation on instantiate, inheritance, and declaring and object variable and how its used to transfer data from one to the other.
I am working on a project for a class, and am having trouble getting my program to automatically calculate the subtotal every time an item is added to the shopping cart list. I've tried sub procedures and functions, but I can't seem to get it to work.
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I am trying to get a running total to come up in the lstGtotal listbox from the list of totals in the 1stTotal listbox but all that I am getting is the numbers 1stTotal listbox to come up[code]...
View 6 RepliesI am writing an application which calculates profit from 3 column values. The SQL is as follows in vb dataset designer; [code] I want to add another column of 'Total' that may display running profit an a separate column. [code]
View 5 RepliesFor my Visual BASIC class we were asked to create a project to compute your checking account balance.Included in the project should be three radio buttons (deposit,check, and service charge), one text box (the amount),and a read only text box which will show the new balance. The balance should be calculated by adding deposits and subtracting checks and service charges; Each of these must return an updated balance. If there is not enough money to cover a check,do not deduct the check amount, but charge a service charge of ten dollars. The problem I have continually run into is keeping a running balance without using do or for loops. Here is a copy of the code i have come up with which will display only what I enter into the amount text box and put it into the balance read only text box; it will not accumulate.
Code:
Private DepositTotalDecimal, CheckTotalDecimal, ServiceChargeTotalDecimal, BalanceDecimal, AmountDecimal As Decimal
Private DepositCountInteger, CheckCountInteger, ServiceChargeCountInteger As Integer
Private Sub PrintButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PrintButton.Click[code]....
how to get running total(adding numbers).
View 1 RepliesHad this issue I was wondering about. This is what it actually DOES then Ill say what I want it to DO. It grabs the word from a notepad I have saved in the directory, and brings it forward onto a form in designated area's and after whomever is done with the word and definition. It'll tell you how many times it's been looked up. Problem is the count applies NOT to the individual words as I'd have liked but EVERY word that has been searched for in the session.: Here's a snip-it
[Code]...
how to get the count to apply for each word individually. Either just within the session or, if possible, keep a constant running total of searched words.
I have created a cystal report that has a running total field on a cost entry on the report. The data comes from a database where the field type is set to numeric with two decimal places. However when i run the report it doesnt add up the total at all it just brings up 13 (unknown where it gets this from as the value is in the thousands.
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I am having an issue with trying to calculate a running total from items in a listbox. I am getting an InvalidCastException with the btnCalc_Click event. I think I understand why I am getting this exception, just not sure exactly how I fix it.
I need to have the lblTotalCost display the Grand Total of all the workshop totals. Ca anyone point me in the right direction here, I have been struggling with this part for about 2 weeks.[code...]
I am using Visaul Studio 2010 to build a Windows Forms application to maintain a table in an SQL Server 2008 database. The table is named CASHBOOK and here are the further details:
DATE | DESCRIPTION | DEBIT | CREDIT | BALANCE
--------|----------------|---------|-----------|---------
1/1/2011| CASH BALANCE | | | 5000
1/1/2011| SALES | 2500 | | 7500
2/1/2011| PURCHASE | | 3000 | 4500
2/1/2011| RENT | | 4000 | 500
2/1/2011| SALES | 5000 | | 5500
I can use CASHBOOKTABLEADAPTER.INSERT(...) to insert appropriately, but my problem is how do I update the BALANCE column?
I'm about to pull my hair out with this program. I need the following program to keep a running total of the total amount due by a customer for books bought. The exercise required the use of a BookSale class with 3 attributes(a quantity,price,and total due) and 2 behaviors(a default constructor and method that keeps a running total). Here is the code for the class:
[code]...
My problem lies in the program keeping a running total. The total due is displayed fine for each quantity and price but not the whole running total. For example,if I enter 1 as quantity and 2 as price and click the Add to Sale button,the Total Due value,which is $2.00,is displayed. However,if I change the quantity to 2 and price to 4,which comes out to $8.00,the $8.00 is not added to the existing $2.00. I feel like I'm missing something elementary and it's driving me crazy. I would work on it some more but it's already after 4 AM here and I need to get some sleep.BTW,this exercise is from a college textbook. However,this isn't an assignment that is due. I just got bored and decided to work on a chapter we didn't have time to get to.
I'm maintaining a Accounting program.. I have a Cash Book Table in SQLserver Databse...field are DATE DESCRIPTION DR CR RT(Running Total is empty record). When in Insert a transaction into that Table the Running Total should give the correct balance for example :
Date Desc Dr Cr RT (Running Total)
1/1/2011 Cash Balance 5000 5000
1/1/2011 Purchase 2000 3000
[code]....
I'm inserting record into that table through Windows form.
I'm creating a small application and want to add function which shows the total running processes in windows. What are the codes for that button?
View 1 Repliesi am cannot for the life of me figure out how to create a running total that will be displayed in a textbox and message box. here is what i need to mimick - [URL] this is my code:
[Code]...
How would I go about using the split method to extract the itemcosts out of a listbox, and then adding them to a running total label?
View 9 RepliesI have a listbox with nothing but integers in it.I want to keep a running total of the integers in a separate text box.
View 3 RepliesI'm developing Asset Management System, it will compute for straight line depreciation, my problem is how to calculate running total on each group that I've extracted from my database.Here's a snippet for my extraction of data
Private Sub cboAType_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboAType.SelectedIndexChanged
ListView1.Items.Clear()
If Not cboAType.Text = "-" Then
[code]....
Is there a way in VS2010 to monitor net usage, and calculate the current/total download and upload while my application is running?
View 9 RepliesHow do I code the total cost to give me a pound sign with the total cost at the moment when the total comes up for an example it gives me 3.6 when I need it to show £3.60 here is the code I have so far. [code]
View 2 RepliesThe pay rates for the project are:
a. Level 1 - $10.00
b. Level 2 - $12.00
c. Level 3 - $14.00
d. Level 4 - $16.00
e. Benefit Deduction Rate - 0.10
f. Overtime Factor - 1.5
For ease of program maintenance, all of the above rates and factors must be stored in module level constants. All references to pay rates in the program must refer to the module level constants.
When the Calculate button is clicked:
a. The value in the Hours text box must be validated to insure that it is numeric value greater than zero.
1. If the value is not valid, a message box must appear as shown below and the user must be offered the option to continue processing or quit the program.
2. If the user chooses to continue processing, the focus must be set to the Hours text box.
3. If the user chooses to quit, the program must close immediately.
b. If the value is valid, the program must calculate and display the total pay in the Total Pay label.
1. The pay rate is determined by which Job Grade radio button is checked.
2. For hours less than or equal to 40, the total pay is the hours times the pay rate.
3. For hours greater than 40, the total pay is 40 hours times the pay rate plus the hours in excess of 40 hours times the pay rate times the Overtime Factor.
4. If the Full Time radio button is selected, the total pay must be reduced by the Benefit Deduction Rate.
5. The value displayed in the Total Pay label must be formatted with a dollar sign and with two decimal
places.
6. The focus must be set to the Hours text box.
Why i get an error when i try to run this code
Code:
Also the message box, both yes and no close the program.....
