How to dynamically add class instances in c#

Question

what i would ask might be silly.

for ex: I have two classes like

public class Login
{
    public String Username;
    public String Pwd;
    public address address1;
}

Address.cs

public class address
{
    public String location;
    public string phonenumber;
}

can i increment the members of the class Login with address2 and address3 as the instances of the class Address using for loop at runtime. Can this be done.. I have an api which is used like that, rather than using address as list/array. please let me know if im confusing.. thanks in advance.

Possible duplicate [How can I dynamically add a field to a class in C#](http://stackoverflow.com/questions/646258/how-can-i-dynamically-add-a-field-to-a-class-in-c-sharp) — Dustin Kingen, Jul 10 '13 at 13:22

score 2 · Answer 1 · answered Jul 10 '13 at 13:19

can i increment the members of the class Login with address2 and address3 as the instances of the class Address using for loop at runtime.

No. If you want more than one address, you should change your class to have a collection of addresses instead of a single field. You can't add fields to an object at execution time. I would suggest using a List<Address>.

Additionally, I'd strongly suggest using properties instead of public fields, and following .NET naming conventions.

Exactly how you expose the collection is up to you, but I'd either expose the List<Address> via a readonly property, or expose methods of AddAddress and RemoveAddress. I'd also try to make Address itself immutable, with a constructor taking all the aspects of it, e.g.

public sealed class Address
{
    private readonly string location;
    private readonly string phoneNumber;

    public string Location { get { return location; } }
    public string PhoneNumber { get { return phoneNumber; } }

    public Address(string location, string phoneNumer)
    {
        // TODO: Validate that it's a valid phone number? Possibly the same
        // for location? Almost certainly prevent either from being null...
        this.location = location;
        this.phoneNumber = phoneNumber;
    }
}

He could use some reflection emit or codedom wizardry to generate a new class a runtime, but that is probably not a desirable solution. — Dustin Kingen, Jul 10 '13 at 13:21
@Romoku: That would allow a new class to be created, but not additional fields to be added to an existing *object*. And yes, it wouldn't be a good idea anyway. — Jon Skeet, Jul 10 '13 at 13:23

score 1 · Answer 2 · answered Jul 10 '13 at 13:19

You should create an array of address classes:

public class Login
{
    public String Username;
    public String Pwd;
    public address[] address;
}

Then use them:

Login l = new Login();
l.address = new address[3];
l.address[0].location = ...
l.address[2].phonenumber = ...
l.address[1].location = ...
l.address[2].location = ...
...etc...

score 0 · Answer 3 · edited May 23 '17 at 12:05

Try using Dictionary, example

class Something
{
   public string Username;
   public string Password;
   public Dictionary<string,address> Address;

   public Something(string username, string password)
   {
      this.Username = username;
      this.Password = password;
      this.Address = new Dictionary<string, address>();
   }
}

add the new variable like this:

void example()
{
     var Something x = new Something("username", "password");
     x.Address.Add("Address1",new address());
     x.Address.Add("Address2",new address());
     x.Address.Add("Address3",new address());
     x.Address.Add("Address4",new address());
     //next address what you want
}

reference: Set array key as string not int?

How to dynamically add class instances in c#

3 Answers3