如何在C#中將串列中的所有專案列印到控制臺？

我正在撰寫一個代碼來獲取輸出（從文本檔案中讀取）：“具有姓名、性別、年齡等實體的人員串列”。但是，當我運行代碼時，我只得到了文本檔案中串列的第一行。這是我的代碼：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace Person_Del
{
    class Program
    {
        public static void Main(String[] args)
        {
            Console.SetIn(new StreamReader("data.txt"));
            List<Person> p = new();
            string data = Console.ReadLine();
            Person obj = new();
            obj.SetData(data,"/");
            p.Add(obj);    
                foreach (var ii in p)
                {
                    Console.WriteLine(ii.GetInfo());
                }
        }
    }
    public class Person
    {
        //static methods
        public static void CheckData(string name, string gender, byte age)
        {
            string msg = null;
            if (string.IsNullOrEmpty(name)) msg  = "Empty Name";
            if (string.IsNullOrEmpty(gender)) msg  = (msg != null ? "; " : "")   "Empty Gender";
            if (age > 125) msg  = (msg != null ? "; " : "")   $"Invalid age ({age})";
            if (msg != null) throw new Exception(msg);
        }
        public static (string, string, byte) Parse(string data, string delimiter)
        {
            try
            {
                string[] arr = data.Split(delimiter);
                string name = arr[0].Trim();
                string gender = arr[1].Trim();
                byte age = byte.Parse(arr[2]);
                return (name, gender, age);
            }
            catch (Exception)
            {
                throw new Exception($"Given data \"{data}\" are invalid.");
            }
        }

        //instance fields
        protected string name;
        protected string gender;
        protected byte age;

        //instance methods
        public string GetName() => name;
        public string GetGender() => gender;
        public byte GetAge() => age;

        public void SetData(string name, string gender, byte age)
        {
            Person.CheckData(name, gender, age);
            this.name = name;
            this.gender = gender;
            this.age = age;
        }
        public void SetData(string data, string delimiter)
        {
            (string, string, byte) value = Person.Parse(data, delimiter);
            string name = value.Item1;
            string gender = value.Item2;
            byte age = value.Item3;
            this.SetData(name, gender, age);
        }
        public string GetInfo() => $"Name:{name}, Gender:{gender}, Age:{age}";


        //new instance methods for homework
        public void SetName(string name) => this.name = name;
        public void SetGender(string gender) => this.gender = gender;

        internal bool SetData()
        {
            throw new NotImplementedException();
        }
    }
}

這是我的文本檔案（data.txt）：

Alice/F/23
David/M/23

注意：我想得到上面兩行的輸出；但是，我得到的只是第一行“Alice/F/23”。

uj5u.com熱心網友回復：

通過首先將所有行讀入陣列：

    public static void Main(String[] args)
    {
        var lines = File.ReadAllLines("data.txt");
        List<Person> people = new();
        foreach(var line in lines){
          Person p = new();
          p.SetData(line,"/");
          people.Add(obj); 
        }   
        foreach (var person in people )
        {
          Console.WriteLine(person.GetInfo());
        }
    }

通過使用 StreamReader 增量讀取：

    public static void Main(String[] args)
    {
        using var sr = new StreamReader("data.txt");
        List<Person> people = new();
        while(!sr.EndOfStream)
        {
          var line = sr.ReadLine();
          Person p = new();
          p.SetData(line,"/");
          people.Add(p); 
        }   
        foreach (var person in people)
        {
          Console.WriteLine(person.GetInfo());
        }
    }

您要問的問題最終源于您只呼叫一次 ReadLine 的事實，但我不建議將您的 StreamReader 存盤在控制臺的標準輸入中。

我還更好地命名了您的變數；爭取有意義的名稱 - 對串列和陣列等使用復數。短期變數可能相對無意義，例如Person p在多個地方使用但壽命較長的變數/變數，嘗試制作它們，使代碼讀起來像一本書：foreach(var person in people)而不是foreach(var ii in p)

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