Question

我想首先按年龄排序此列表中的名称（我到目前为止已经完成），但我想知道如何在打印到新文件之前再按姓氏对这些名称进行排序。例如，如果我有5个年龄在20岁且姓名不同的人，我怎样才能确保这5个人按字母顺序递增？

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Answer 1

Linq是你的朋友。您可以在一行中重写所有代码：

peeps.OrderBy(x => x.Age).ThenBy(x => x.LastName);

这就是它的全部:)。你可以摆脱所有那些IComparable垃圾，那是旧学校。

编辑：对于IComparable，你可以这样做：

    public int CompareTo(object obj)
    {
        Person other = (Person)obj;

        if (age < other.age)
            return -1;

        if (String.Compare(vorname, other.vorname) < 0)
            return -1;

        return 1;
    }

似乎可以为我的快速测试工作，但测试更多：）。

Answer 2

您可以使用Linq：

 people.OrderBy(person => person.age)
     .ThenBy(person => person.LastName);

Answer 3

有点老式，但仍然。您可以使用Comparers并在以后根据需要使用它们：

    public class AgeComparer: Comparer<Person> 
    {
        public override int Compare(Person x, Person y)
        {   

           return x.Age.CompareTo(y.Age);      
        }    
    }
    public class LastNameThenAgeComparer: Comparer<Person> 
    {
        public override int Compare(Person x, Person y)
        {       
            if (x.LastName.CompareTo(y.LastName) != 0)
            {
               return x.LastName.CompareTo(y.LastName);
            }
            else (x.Age.CompareTo(y.Age) != 0)
            {
               return x.Age.CompareTo(y.Age);
            }    
        }    
    }
//// other types of comparers

用法：

personList.Sort(new LastNameThenAgeComparer());

Answer 4

LINQ +扩展方法

class Program
{
    static void Main(string[] args)
    {
        try
        {
            "inputNames.txt".ReadFileAsLines()
                            .Select(l => l.Split(','))
                            .Select(l => new Person
                            {
                                vorname = l[0],
                                nachname = l[1],
                                age = int.Parse(l[2]),
                            })
                            .OrderBy(p => p.age).ThenBy(p => p.nachname)
                            .WriteAsLinesTo("outputNames.txt");
        }
        catch (Exception e)
        {
            Console.Error.WriteLine(e.Message);
        }
    }
}
public class Person
{
    public string vorname { get; set; }
    public string nachname { get; set; }
    public int age { get; set; }

    public override string ToString()
    {
        return string.Format("{0} {1}\t{2}", this.vorname, this.nachname, this.age);
    }
}
public static class ToolsEx
{
    public static IEnumerable<string> ReadFileAsLines(this string filename)
    {
        using (var reader = new StreamReader(filename))
            while (!reader.EndOfStream)
                yield return reader.ReadLine();
    }
    public static void WriteAsLinesTo(this IEnumerable lines, string filename)
    {
        using (var writer = new StreamWriter(filename))
            foreach (var line in lines)
                writer.WriteLine(line);
    }
}

Answer 5

这就是我如何用一些评论来实现这样一个人类。

//sort a person object by age first, then by last name
    class Person : IComparable<Person>, IComparable
    {
        public string LastName { get; }
        public string FirstName { get; }
        public int Age { get; }

        public Person(string vorname, string nachname, int age)
        {
            LastName = vorname;
            FirstName = nachname;
            Age = age;
        }

        // used by the default comparer
        public int CompareTo(Person p)
        {
            // make sure comparable being consistent with equality; this will use IEquatable<Person> if implemented on Person hence better than static Equals from object
            if (EqualityComparer<Person>.Default.Equals(this, p)) return 0;

            if (p == null)
                throw new ArgumentNullException(nameof(p), "Cannot compare person with null");

            if (Age.CompareTo(p.Age) == 0)
            {
                return LastName.CompareTo(p.LastName);
            }
            return Age.CompareTo(p.Age);
        }

        // explicit implementation for backward compatiability 
        int IComparable.CompareTo(object obj)
        {
            Person p = obj as Person;
            return CompareTo(p);
        }

        public override string ToString() => $"{LastName} {FirstName} \t {Age}";
    }

使用名/姓和年龄C＃对名称列表进行排序

5 个答案: