Constructor '' cannot call itself

Question

I'm trying to make this class called 'Medico' that translates to Doctor, but in "this" it appears the error

Constructor 'Medico.Medico(string, string, int, string, string) cannot call itself.

I wanted to make a doctor class to add data in it, to a list view.

public class Medico
{
    public string Nome { get; set; }
    public string Especialidade { get; set; }

    private int _NIF;
    private DateTime _inicio;
    private DateTime _fim;

    public int NIF
    {
        get { return _NIF; }
        set
        {
            _NIF = value;
            if (_NIF < 99999999)
            {
                _NIF = 0;
            }
        }
    }

    public DateTime Inicio
    {
        get { return _inicio; }
        set
        {
            _inicio = value;
        }
    }

    public DateTime Fim
    {
        get { return _fim; }
        set
        {
            _fim = value;
        }
    }


    public Medico(string nome, string especialidade, int _NIF, DateTime _inicio, DateTime _fim)

    {
        Nome = nome;
        Especialidade = especialidade;
        NIF = _NIF;
        Inicio = _inicio;
        Fim = _fim;

    }

    public Medico(string nome, string especialidade, int _NIF, string _inicio, string _fim)
        : this(nome, especialidade, _NIF, _inicio, _fim) {            

    }

    public override string ToString()
    {
        return Inicio.ToString() + Fim.ToString();
    }
}

Gilad Green · Answer 1 · 2017-06-01T09:02:18.233

In your second constructor you are just passing the parameters you got.. so its calling itself.

this(nome, especialidade, _NIF, _inicio, _fim)

Instead cast the _inicio and _fim to a DateTime and it'll call the first constructor.

See Converting a String to a DateTime

this(nome, especialidade, _NIF, DateTime.ParseExact(_inicio,"YourFormat"), 
     DateTime.ParseExact(_fim,"YourFormat"))

If you know the format is a correct DateTime format you can use also DateTime.Parse()

In general you might want to change and use object-initializers instead of having many constructors. More about when to use see:

In addition for your properties with the default implementation better use the auto-properties:

public DateTime Fim { get; set; }
public DateTime Inicio { get; set; }

@Simao Pina - Does the answer above help you solve the problem? — Gilad Green, Jun 02 '17 at 13:57

pitersmx · Answer 2 · 2017-06-01T09:02:27.470

If you want to create several constructors for Medico with different input parameters, just create a new medico constructor, without this:

public Medico(string nome, string especialidade, int _NIF, DateTime _inicio, DateTime _fim)
{
    Nome = nome;
    Especialidade = especialidade;
    NIF = _NIF;
    Inicio = _inicio;
    Fim = _fim;
}

public Medico(string nome, string especialidade, int _NIF, string _inicio, string _fim)
{
    // here convert _inicio and _fim to DateTime
    // And call the first constructor method with new parameters
    Medico(nome, especialidade, _NIF, inicioDateTime, fimDateTime);
}

score 0 · Answer 3 · answered Jun 01 '17 at 08:52

The following constructor definition:

public Medico(string nome, string especialidade, int _NIF, string _inicio, string _fim)
        : this(nome, especialidade, _NIF, _inicio, _fim)

Means to call another constructor of this class and pass the values in this(...). Since you just pass the strings for _inicio and _fim the constructor tries to call itself. I suggest you want to call the other constructor:

public Medico(string nome, string especialidade, int _NIF, DateTime _inicio, DateTime _fim)

to do taht you would need to convert the strings to DateTimes first. Perhaps something like this:

public Medico(string nome, string especialidade, int _NIF, string _inicio, string _fim)
            : this(nome, especialidade, _NIF, DateTime.ParseExact(_inicio, 'yyyyMMdd',CultureInfo.InvariantCulture) , DateTime.ParseExact(_fim,'yyyyMMdd',CultureInfo.InvariantCulture))

Just change the pattern

Constructor '' cannot call itself

3 Answers3