How do return the reference to a specific structure in a list of structs?

Question

 public struct bank_account
    {
        public string name;
        public string credit_card_number;
    }

    private List<bank_account> all_accounts = new List<bank_account>();

    public bank_account getAccount(string card_number)
   {

        bank_account holder; // this pointer is the wrong way to do it but im used to c++
        foreach(bank_account acc in all_accounts)
        {
            if (card_number == acc.credit_card_number)
               holder = acc;
        }

        return holder;
    }

Im new to c#. Use to c++. Normally in c++ the holder variable would be a pointer. and all i want it to do is point to the correct bank_account structure so i could return it so another function could access the structs variables. How is this done in c#?

Answer 1

Your code is basically fine, take a look at LINQ which will make things a lot easier to read.

public bank_account getAccount(string card_number)
{
    return allAccounts.FirstOrDefault(x => x.CreditCardNumber == cardNumber);
}

And as others have mentioned: dont use struct for this, use a class. If you use a struct you will always return a struct with empty strings in it if the credit card number was not found. If your credit card number was found, you will returrn a copy of the original struct, not the struct itself.

If you use a class you will return eiter a reference to the original object or null if the number was not found. Check out C#/C++ struct differences, they really do behave different.

See the following sample to get an idea how it could look like:

public class BankAccount
{
    // don't publish your private fields, use properties for public access
    public string Name { get; set; }
    public string CreditCardNumber { get; set; }
}

public class BankAccounts
{
    private List<BankAccount> allAccounts = new List<BankAccount>();

    public BankAccount GetAccount(string cardNumber)
    {
        return allAccounts.FirstOrDefault(x => x.CreditCardNumber == cardNumber);
    }
}

Answer 2

Let me make it easy, use the var

foreach(var acc in all_accounts) { 
   if (card_number == acc.credit_card_number)
      return acc; 
}