1

Problem: I am trying to update a List. If a certain item's ID already exists in the List, I want to add onto that item's quantity. If not, then I want to add another item to the list.

            cart = (List<OrderItem>)Session["cart"];

            for(int counter = cart.Count-1; counter >= 0; counter--)
            {
                if (cart[counter].productId == item.productId)
                {
                    cart[counter].productQuantity += item.productQuantity;
                }
                else if (counter == 0)
                {
                    cart.Add(item);
                }
            }

cart[counter] and item represent an instance(s) of a custom object of mine. Currently when I finally find a matching ID, everything APPEARS as though it should work, but I get a StackOverflowException thrown in my custom object class.

    public int productQuantity
    {
        get
        {
            return _productQuantity;
        }
        set
        {
            productQuantity = value;
        }
    }

It gets thrown right at the open-bracket of the "set". Could somebody please tell me what the heck is wrong because I've been going at this for the past 2+ hours to no avail. Thank you in advance.

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4
  • 1
    On a side note, a dictionary or hashset may work better for you; no collection traversal would be necessary in that case. Commented Jun 1, 2010 at 4:35
  • Is there a reason that you return _productQuantity and set productQuantity? I usually use the same backing member for that. Commented Jun 1, 2010 at 4:38
  • @Rob: I thought it was a naming convention/data-hiding thing. I don't remember when/where I first saw it but I'd been coding my school projects like that and up until now I've never encountered a problem. I come from a Java background so the set/get properties in C# -- in Java I'd actually have to code getter and setter methods for that functionality. I think I probably just saw some code snippets somewhere before and got things mixed-up in my head. Commented Jun 1, 2010 at 5:07
  • 1
    You should use Pascal case (ProductQuantity) for your properties rather than Camel case (productQuantity) - use Camel case for your instance fields, it might make problems like these easier to spot for you. Commented Jun 1, 2010 at 5:25

4 Answers 4

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8

the problem is in your setter of the productQuantity

it should read:

set
    {
        _productQuantity= value;
    }

edit (naming convention):

public class Vertex3d
{
    //fields are all declared private, which is a good practice in general 
    private int _x; 

    //The properties are declared public, but could also be private, protected, or protected internal, as desired.
    public int X
    { 
        get { return _x; } 
        set { _x = value; } 
    }
}
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5 Comments

on a side note: I didn't look for anyother bugs in your code posted above, just this particular one.
+1 1,000 times if I could; subtle bugs like that are one reason for paired-programming (or at least having fresh eyes stare at your code).
Dear God good-call. I didn't expect to get such a quick response either. THANKYOUTHANKYOU! I can't remember where I learned to code my properties but for some reason in the sets I never named the variable the same as I did in the gets. I thought it was a naming-convention as well as data-hiding thing... So another question: What's the proper naming convention for properties??
@KSwift: not sure how to format the comment box here sry about that. An example with few comments follows: public class Vertex3d{ private int _x; //fields are all declared private, which is a good practice in general //The properties are declared public, but could also be private, protected, or //protected internal, as desired. public int X{ get { return _x; } set { _x = value; } } } ..this is a very general answer but hopefully something useful :)
Right on. Thank you VoodooChild. I talked with some coworkers where I'm interning at and they made it clear to me exactly what happened. I gotta make sure I'm actually getting/setting the PRIVATE variable in the public property and not getting/setting the public property like I was doing in the set.
3

Replace productQuantity = value; with _productQuantity = value; (you're recurring infinitely by calling the setter over and over)

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1 Comment

Thank you for the response as well but VooDoo child was first. I'm still giving you a +1 though. :-)
3

Why not just use this instead? public int productQuantity { get; set; }

But the flaw was in the _

public int productQuantity {
    get {
        return _productQuantity;
    }
    set {
        _productQuantity = value;
    }
}

cart = (List<OrderItem>)Session["cart"];
int index = cart.Find(OrderItem => OrderItem.productId == item.productId);
if(index == -1) {
    cart.Add(item);
} else {
    cart[index].productQuantity += item.productQuantity;
}
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2 Comments

Thank you for the response as well but VooDoo child was first. I'm still giving you a +1 though. :-) As for your suggestion... I've never been formally taught about Lambda expressions, and although I've seen them before I've never really understood what they're for/how they operate.
you should definitely read a tutorial about them. They are quite easy to follow (basic ones anyways) and very handy
2 
public int productQuantity
{
   get
   {
      return _productQuantity;
   }
   set
   {
      _productQuantity = value; //this should be an assignment to a member variable.
   }
}
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1 Comment

Thank you for the response as well but VooDoo child was first. I'm still giving you a +1 though. :-)

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