I would like to convert the following procedure to use Linq, but I'm not sure how to accomplish it, ForEach or Sum?

    public int GetBalance()
        int balance = 0;

        foreach (IDenomination denomination in Account)
            balance += denomination.Currency * denomination.BillCount;

        return balance;

Account is a property in the class:

public List<IDenomination> Account { get; set; }

Or you could do it in two steps, like you do it now. First calculate for each denomination and then sum:

int balance = Account.Select(denom => denom.Currency * denom.BillCount).Sum();
  • \$\begingroup\$ Another awesome answer, thank you! I'm still somewhat of a noob with Linq so I really appreciate the help! \$\endgroup\$ – TrevorBrooks Feb 20 '15 at 17:44
  • 1
    \$\begingroup\$ btw. Free upside of doing things this way: Linq's Sum() does overflow detection for you. Downside of doing things this way: its probably a little bit slower than your original foreach. (and of course the major upside is that reads better) \$\endgroup\$ – Hirle Feb 20 '15 at 17:59
  • \$\begingroup\$ Agreed, it's definitely a bit of a trade off. \$\endgroup\$ – TrevorBrooks Feb 20 '15 at 18:01
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    \$\begingroup\$ @Hirle You can actually do the lambda inside the Sum: var balance = Account.Sum(denom => denom.Currency * denom.BillCount); \$\endgroup\$ – Dan Lyons Feb 20 '15 at 18:58
  • \$\begingroup\$ Cool, didnt know that! \$\endgroup\$ – Hirle Feb 20 '15 at 19:40

You could use the Aggregate extension method:

int balance = Account.Aggregate(0, (old, item) => old + item.Currency * item.BillCount);

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