How to add an element to a list?

Question

What is the correct syntax to call the method Add_Pessoa class ClsPessoa by a List?

public class ClsPessoa
{
    private static string PSTR_Nome = "";
    private static DateTime PDT_DataNascimento;
    private static string PSTR_Email = "";

    public ClsPessoa()
    {
    }

    static public string Nome
    {
        get { return PSTR_Nome; }
        set { PSTR_Nome = value; }
    }

    static public DateTime DataNascimento
    {
        get { return PDT_DataNascimento; }
        set { PDT_DataNascimento = value; }
    }

    static public string Email
    {
        get { return PSTR_Email; }
        set { PSTR_Email = value; }
    }       

    public void Add_Pessoa(string PV_Nome, DateTime PV_DataNascimento, string PSTR_Email)
    {
        Nome = PV_Nome;
        DataNascimento = PV_DataNascimento;
        Email = PSTR_Email;
    }

Something like that?

var pessoas = new List<ClsPessoa>();
pessoas[0].Add_Pessoa(TXT_Nome.Text, DTP_DataNascimento.DisplayDate, TXT_Email.Text);

Answer 1

Don’t confuse the object Pessoa and the object List<Pessoa>. These are separate things. So you can’t "add a person to a person". It looks like the phrase doesn’t make sense. You can "add a person to a list of people". Then operations are separated.

If you are going to add, you do not choose in which position you will place. And just as in array, you have create an instance of the desired class and then add the instance:

var pessoas = new List<ClsPessoa>();
pessoas.Add(new ClsPessoa() {Nome = TXT_Nome.Text,
                             DataNascimento = DTP_DataNascimento.DisplayDate,
                             Email = TXT_Email.Text});

If you want to change the content of position 0 in the list then use:

pessoas[0] = new ClsPessoa() {Nome = TXT_Nome.Text,
                              DataNascimento = DTP_DataNascimento.DisplayDate,
                              Email = TXT_Email.Text});

Or if you want to move a property:

pessoas[0].Email = TXT_Email.Text;

But there’s a better way to build the whole class:

public class Pessoa {
    public Pessoa(string nome, DateTime dataNascimento, string email) {
        Nome = nome ?? ""; //esquisito, mas é o que tinha no código original
        DataNascimento = dataNascimento;
        Email = email ?? "";
    }
    public string Nome { get; set;}
    public DateTime DataNascimento { get; set; }
    public string Email { get; set; }
}

I put in the Github for future reference.

Looks like it got simpler. With better names, without using hungarian notation which is horrible and doesn’t help at all, without using anything out of standard. With simplified syntax of automatic properties. Using the constructor in the right way and avoiding an auxiliary method that was of no use. And mostly fixing the problem of static limbs. If you are going to create a class that needs to be instantiated, that is, you are going to create an object with data in it, the members of the object cannot be static.

You can still improve several things in this class. But let’s take parts. One of them would be not even having a builder. In this case it is not being especially useful. I just don’t say that it is completely unnecessary because I don’t know the requirement. I can see some reason to have it.

If you really need to have a class to better abstract a list of people, then another class needs to be created. But this is already another subject.

If you do this, then you can change the above syntax a little, although it won’t make much difference. I find the first form more readable. Although you can make the shape below more readable too. But leave it for later, I will not fill with news in your head.

pessoas.Add(new Pessoa(Nome.Text,
                       DataNascimento.DisplayDate,
                       Email.Text));

I know that I presented you several new things, do a search, if you find nothing here, ask a question about what you were left with doubt (one question per subject) and we will answer.

Learn more about static members on:

• What is the function of a static method?
• How static variables behave in . NET?
• Static classes and classes with static methods