Do not check in the generic list of a item there is

Question

I wish to make a small insurance application. The application asks your name and then checks if name already exists; if they exist then you get a message this name is already used.

if not then you will be asked what for insurance do you want and then on the screen you get a message the name is correctly signed up.

and i have a function that lists all my client's names and the kind of insurance as a generic list

I make a generic list and in my function i use foreach so i can print every item in the generic list everything works good but if i add a person to my list and i try back and write the same name i don't get error.

Question: Why I don't get a error? what is the problem actually?

Thank you in advance

my code is here under:

public static List<string> klantgegevens = new List<string>();

public static void Main(string[] args)
{
    retry:

        string naam;
        int verzekeringkeuze;
        string alleklantgegevens;

        Console.WriteLine("wat is u naam");
        naam = Console.ReadLine();

        if (klantgegevens.Contains(naam))
        {
            Console.WriteLine("deze naam bestaat al");
        }
        else
        {
            Console.WriteLine("kies u soort verzekering: 1-auto,2-leven,3-woning");
            verzekeringkeuze = int.Parse(Console.ReadLine());

            switch (verzekeringkeuze)
            {
                case 1:
                    Console.WriteLine(alleklantgegevens = $"{naam}:auto");
                    break;

                case 2:
                    Console.WriteLine(alleklantgegevens = $"{naam}:leven");
                    break;

                case 3:
                    Console.WriteLine(alleklantgegevens = $"{naam}:woning");
                    break;

                default:
                    break;
            }

            Console.WriteLine($"{naam} werd correct ingeschreven");
            Console.ReadLine();
            alleklantgegevens = $"{naam}:{verzekeringkeuze}";
            klantgegevens.Add(alleklantgegevens);
        }
        Printall();
        goto retry;
 }

 public static void Printall()
 {
     foreach (string gegevens in klantgegevens)
     {
         Console.WriteLine($"alle klantgegevens:{gegevens}");
     }
     Console.ReadLine();
 }

Answer 1

没有错误，因为您检查 Contains(naam) 而不是 $"{naam}:{verzekeringkeuze}" 这是您放入列表中的内容。