namespaces and classes - Organizing your code - Console App, Write, ReadLine, int, TryParse, if/else statement

Head First C#:
A Learner's Guide to Real-World Programming
with C# and .NET
Kindle版

開発環境

Head First C Sharp: A Learner’s Guide to Real-World Programming with C Sharp and .NET (Andrew Stellman(著)、Jennifer Greene(著)、O’Reilly Media)の Chapter 3(namespaces and classes - Organizing your code)、p.143(Exercise)の解答を求めてみる。

コード

Program.cs

namespace PickRandomCards;

class Program
{
    static void Main(string[] args)
    {
        Console.Write("Enter the number of cards to pick: ");
        string? line = Console.ReadLine();
        if (int.TryParse(line, out int numberOfCards))
        {
            foreach (string card in CardPicker.PickSomeCards(numberOfCards))
            {
                Console.WriteLine(card);
            }
        }
        else
        {
            Console.WriteLine($"Invalid input '{line}'");
        }
    }
}

入出力結果(Terminal, Zsh)

Enter the number of cards to pick: 5
3 of Hearts
10 of Spades
King of Spades
9 of Hearts
6 of Diamonds

Enter the number of cards to pick: 10
7 of Diamonds
King of Hearts
3 of Diamonds
4 of Diamonds
Queen of Hearts
4 of  Clubs
Jack of Spades
Ace of  Clubs
5 of Diamonds
8 of Hearts

Enter the number of cards to pick: cards
Invalid input 'cards'