C# 排序的多种实现方式

01 数组排序

最常见的排序是对一个数组排序，比如：

int[] aArray = new int[8] { 18, 17, 21, 23, 11, 31, 27, 38 };

第一种：我们最熟悉的冒泡排序法：即每个值都和它后面的数值比较，每次拿出最小值

static void Main(string[] args)

{

int[] aArray = new int[8] { 18, 17, 21, 23, 11, 31, 27, 38 };

for (int j = 0; j < aArray.Length - 1; j++)

{

for (int i = 0; i < aArray.Length - 1; i++)

{

if (aArray[i] > aArray[i + 1])

{

int temp = aArray[i];

aArray[i] = aArray[i + 1];

aArray[i + 1] = temp;

}

}

}

foreach (var a in aArray)

{

Console.Write($"{a} ");

}

Console.ReadKey();

}

第二种：利用Array.Sort排序：

① 升序排列：

static void Main(string[] args)

{

int[] aArray = new int[8] { 18, 17, 21, 23, 11, 31, 27, 38 };

Array.Sort(aArray);

foreach (var a in aArray)

{

Console.Write($"{a} ");

}

Console.ReadKey();

}

② 降序排列：先升序排列，然后对数组反转

static void Main(string[] args)

{

int[] aArray = new int[8] { 18, 17, 21, 23, 11, 31, 27, 38 };

Array.Sort(aArray);

Array.Reverse(aArray);

foreach (var a in aArray)

{

Console.Write($"{a} ");

}

Console.ReadKey();

}

02 List排序

大多数时候，我们需要将list集合里面的数据进行排序，

① 如果list直接放置的数值类型的数据就比较简单，比如：

List<int> aList = new List<int> { 18, 17, 21, 23, 11, 31, 27, 38 };

方法一：利用List<T> 自带的Sort排序方法

升序排列：

aList.Sort();

降序排列：

aList.Sort();

aList.Reverse();

-. sort也可以用如下方式操作：

list.Sort((a, b) => a.CompareTo(b));//升序

list.Sort((a, b) => b.CompareTo(a));//降序

方法二：利用List的OrderBy与OrderByDescending方法

升序排列：

List<int> aList = new List<int> { 18, 17, 21, 23, 11, 31, 27, 38 };

aList = aList.OrderBy(a => a).ToList();

降序排列：

List<int> aList = new List<int> { 18, 17, 21, 23, 11, 31, 27, 38 };

aList = aList.OrderByDescending(a => a).ToList();

方法三：利用link，这种感觉和方法二是一回事

List<int> aList = new List<int> { 18, 17, 21, 23, 11, 31, 27, 38 };

aList = (from a in aList orderby a ascending select a).ToList();//升序

aList = (from a in aList orderby a descending select a).ToList();//降序

②如果list存放的是一个类型，比如：

方法一： 一个集合存放学生的信息，按照学生的成绩升序排列：这里列举了2种方法，方法一注释了

static void Main(string[] args)

{

List<Student> stuList = new List<Student>

{

new Student() {name = "zyr", age = 23, score = 99},

new Student() {name = "zls", age = 25, score = 95},

new Student() {name = "zsq", age = 27, score = 100},

new Student() {name = "zlw", age = 15, score = 69},

new Student() {name = "ywe", age = 17, score = 72},

new Student() {name = "asw", age = 29, score = 58}

};

//方法1 升序

//stuList.Sort((x, y) => x.score.CompareTo(y.score));

//方法2 升序

stuList = stuList.OrderBy(stu=>stu.score).ToList();

foreach (var stu in stuList)

{

Console.WriteLine($"{stu}");

}

Console.ReadKey();

}

public class Student

{

public string name { get; set; }

public int age { get; set; }

public int score { get; set; }

public override string ToString()

{

return $"姓名是：{name},年龄是：{age},得分是：{score}";

}

}

方法二： 加入这个学生成绩有重复的，对于重复的成绩按照年龄再排序：这里列举了2种方法，方法一注释了

static void Main(string[] args)

{

List<Student> stuList = new List<Student>

{

new Student() {name = "zyr", age = 23, score = 99},

new Student() {name = "zls", age = 25, score = 95},

new Student() {name = "zls", age = 22, score = 95},

new Student() {name = "zsq", age = 27, score = 100},

new Student() {name = "zlw", age = 15, score = 69},

new Student() {name = "ywe", age = 17, score = 72},

new Student() {name = "asw", age = 29, score = 58},

new Student() {name = "ywe", age = 18, score = 72},

new Student() {name = "zsq", age = 16, score = 100},

};

//方法1 升序

//stuList.Sort((x, y) =>

//{

// int ret = x.score.CompareTo(y.score);

// if (ret == 0)

// {

// return x.age.CompareTo(y.age);

// }

// else

// {

// return ret;

// }

//});

//方法2 升序

//stuList = stuList.OrderBy(stu=>stu.score).ThenBy(stu => stu.age).ToList();

foreach (var stu in stuList)

{

Console.WriteLine($"{stu}");

}

Console.ReadKey();

}

public class Student

{

public string name { get; set; }

public int age { get; set; }

public int score { get; set; }

public override string ToString()

{

return $"姓名是：{name},年龄是：{age},得分是：{score}";

}

}