Avoid duplicated id in list c#

Question

I am doing a list exercise where I have to enter the employee id, but there should be no repetition of id. I would like to know how to use the foreach to avoid checking and blocking if a repeated value is inserted.

Follows the code of the executable class:

Console.WriteLine("Quantos empregados serão registrados?");
int n = int.Parse(Console.ReadLine());

        List<Empregado> lista = new List<Empregado>();

        for(int i=1; i<=n; i++)
        {
            Console.WriteLine("Empregado #{0}",i);

            Console.WriteLine("Digite o ID:");
            int id = int.Parse(Console.ReadLine());
            foreach (int obj in lista)
            {
                if (id!=null)
                {
                    Console.WriteLine("Id já existe, digite outro:");
                    id = int.Parse(Console.ReadLine());

                }
        }

Answer 1

I’ll show you a way you can achieve what you want to do.

That way you can use the Linq to check if the entered id already exists in your list:

//Usando linq para verivicar se o id digitado já existe na sua lista
if (lista.Any(x=> x.Id == id))
{
    Console.WriteLine("Id já existe, digite outro:");
    i--; //Se existe, decrementa o contador para que ele possar informar novamente
}
else
{
    //Adicione aqui seu novo Empregado a sua Lista
}

In case you haven’t learned about Linq and you don’t understand what you’re doing, try to continue your implementation using the for or foreach. It’s important that you understand what you’re doing.

Note that in your code in the question there are problems and neither the implementation with the foreach you achieved.

Here for example: foreach (int obj in lista) you are trying to go through your list of type Empregado, but it’s setting her up as int. That won’t work.

Another, less serious problem is this: if (id!=null) where your id is of type int and will never be null. Read here if you want to understand more about it too.