C# operands error

Question

I am trying to calculate the total for a list in my C# program, I have gotten help from several people in my class and we can't seem to find the problem, my code is,

        int totalB = 0;

        Cards.ForEach(delegate(ConsoleApplication1.Program.CreditCard Balance)
        {
            totalB= totalB + Balance;
        });

The error is this Error 1 Operator '+' cannot be applied to operands of type 'int' and 'ConsoleApplication1.Program.CreditCard'

Any help for this would be much appreciated as I have no idea and neither do the people that tried to help me with this issue

Answer 1

As far as getting sum of list is concerned. it is as simple as (assuming Cards is a list)

 Cards.Sum(x=>x.YourPropertyToSum);

Your Error:

The error is this Error 1 Operator '+' cannot be applied to operands of type 'int' and 'ConsoleApplication1.Program.CreditCard'

you are trying to add an int with ConsoleApplication1.Program.CreditCard (what is this) which is obviously not a type that can be added to int. Hence the error you are getting.

Answer 2

I'm guessing you have a class like:

partial class CreditCard
{
    public int Balance {get; set;}
}

So following what you have, explicitly, you most likely intended:

int totalB = 0;

Cards.ForEach(delegate(ConsoleApplication1.Program.CreditCard card)
{
    totalB = totalB + card.Balance;
});

This iterates over each item in your Cards collection, and adds the value of the Balance property to totalB. Note I have called the variable card in the delegate to further illustrate what is going on - the delegate will be called once for each item in the collection. Inside, you can pick out the Balance property and add it to totalB.

---

Note you can also do this in a number of other ways:

1. Using LINQ:

   int totalB = Cards.Sum(card => card.Balance);
   

2. Using a lambda expression instead of an explicit delegate:

   int totalB = 0;
   
   Cards.Foreach(card => {totalB += card.Balance;});
   

3. Using a foreach loop:

   int totalB = 0;
   
   foreach(CreditCard card in Cards)
       totalB += card.Balance;
   

(If you are not familiar with it, the x += y is the same as x = x + y.)