为 C# 中的对象列表提供控制台输入

Question

I want a program to write info about persons to a file in C#...so I have the following class

class Person
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

    }

And the class that writes to the file is this one:

       class Adding
     {
        public static void AddedPersons(List<Person> persons,string path)
        {
            List<string> content = new List<string>();
            
            content.Add("FirstName , LastName");

            foreach (var person in persons)
            {
                content.Add($"{person.FirstName}, {person.LastName}");
            }

            System.IO.File.WriteAllLines(path,content);
        }
    }

And the main method...

static void Main(string[] args)
        {
           
            List<Person> persons = new List<Person>();

           
            string path = @"C:\Users\cosmi\Desktop\Citire\Test.csv";
            
            Elements(persons);
            Adding.AddedPersons(persons, path);
            
            Console.ReadLine();

        }

And the elemnts that I am adding in the List are hard codded in the following method...

 public static void Elements(List<Person> persons)
        {

            persons.Add(new Person() { FirstName = "Cosmin", LastName = "Ionut" });
            persons.Add(new Person() { FirstName = "Bianca", LastName = "Elena" });
    
        }

So what I want is to be able to add those persons as a console input, not hard coded in a method

Answer 1

One idea would be to write a method that gets the first and last name from console input and returns a new Person object. Below I've added it as a static method on the Person class.

I also added an instance method called AsCsvItem which returns the person in CSV format ( "FirstName, LastName" ), which will come in handy later.

And finally I added a static SaveToFile method that will save a list of people to the specified file path in Csv format.

Note that these new methods could exist somewhere else, I just put them in the Person class for convenience:

class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public static Person FromConsoleInput()
    {
        var person = new Person();

        Console.Write("Enter first name: ");
        person.FirstName = Console.ReadLine();

        Console.Write("Enter last name: ");
        person.LastName = Console.ReadLine();

        return person;
    }

    public string AsCsvItem()
    {
        return $"{FirstName} , {LastName}";
    }

    public static void SaveToFile(List<Person> people, string path)
    {
        // Create a list with the column headers
        List<string> content = new List<string> {"FirstName , LastName"};

        // Add a line for each person
        content.AddRange(people.Select(person => person.AsCsvItem()));

        // Save it to the file path
        File.WriteAllLines(path, content);
    }
}

Then you can just call the FromConsoleInput method in a loop to populate a list of people, and the SaveToFile method to save them to the csv file. Below I'm using numPeople to determine how many people we should add:

var numPeople = 2;
var people = new List<Person>();

for (var i = 0; i < numPeople; i++)
{
    Console.WriteLine($"Enter person #{i + 1} info:");
    people.Add(Person.FromConsoleInput());
}

Person.SaveToFile(people, @"c:\temp\people.csv");

Answer 2

If you want a smaller change, I would do this:

public static List<Person> GetElements()
{
    List<Person> persons = new List<Person>();
    do
    {
        var person = new Person();

        Console.Write("Enter first name: ");
        person.FirstName = Console.ReadLine();
        Console.Write("Enter last name: ");
        person.LastName = Console.ReadLine();
        persons.Add(person);

        Console.Write("Press Y to enter another person, other key to finish.");
    } while (Console.ReadKey().Key == ConsoleKey.Y);

    return persons;
}

The code is pretty straightforward. I wouldn't create the list in Main but instead let this method create and populate the list, so all actions related to creating the list are in one place. Furthermore, methods are usually verbs to clearly state what they do. With void Elements(List<Person>) you can't guess what it does at all.