[C# .NET] 数组排序 Arrays

本示例说明如何在C＃中对数组进行排序。 可以使用内部使用Quicksort算法的静态方法Array.Sort对Array进行排序。

Sorting array of primitive types-基本类型数组排序

To sort array of primitive types such as int, double or string use method Array.Sort(Array) with the array as a paramater. The primitive types implements interface IComparable, which is internally used by the Sort method (it calls IComparable.Com­pareTo method). See example how to sort int array:

基本类型数组排序

// sort int array
int[] intArray = new int[5] { 8, 10, 2, 6, 3 };
Array.Sort(intArray);
// write array
foreach (int i in intArray) Console.Write(i + " ");  // output: 2 3 6 8 10

字符串数组排序:

// sort string array
string[] stringArray = new string[5] { "X", "B", "Z", "Y", "A" };
Array.Sort(stringArray);
// write array
foreach (string str in stringArray) Console.Write(str + " "); // output: A B X Y Z

 

Sorting array of custom type using delegate-利用委托自定义排序

To sort your own types or to sort by more sophisticated rules, you can use delegate to anonymous method. The generic delegate Comparison<T> is declared as public delegate int Comparison<T> (T x, T y). It points to a method that compares two objects of the same type. It should return less then 0 when X < Y, zero when X = Y and greater then 0 when X > Y. The method (to which the delegate points) can be also an anonymous method (written inline).

Following example demonstrates how to sort an array of custom type using the delegate to anonynous comparison method. The custom type in this case is a class User with properties Name and Age.

 

// array of custom type
User[] users = new User[3] { new User("Betty", 23),  // name, age
                             new User("Susan", 20),
                             new User("Lisa", 25) };

// sort array by name
Array.Sort(users, delegate(User user1, User user2) {
                    return user1.Name.CompareTo(user2.Name);
                  });
// write array (output: Betty23 Lisa25 Susan20)
foreach (User user in users) Console.Write(user.Name + user.Age + " ");

 

// sort array by age
Array.Sort(users, delegate(User user1, User user2) {
                    return user1.Age.CompareTo(user2.Age); // (user1.Age - user2.Age)
                  });
// write array (output: Susan20 Betty23 Lisa25)
foreach (User user in users) Console.Write(user.Name + user.Age + " ");

 

Sorting array using IComparable--利用IComparable接口排序

If you implement IComparable interface in your custom type, you can sort array easily like in the case of primitive types. The Sort method calls internally IComparable.Com­pareTo method.

 

// custom type
public class User : IComparable
{
  // ...

  // implement IComparable interface
  public int CompareTo(object obj)
  {
    if (obj is User) {
      return this.Name.CompareTo((obj as User).Name);  // compare user names
    }
    throw new ArgumentException("Object is not a User");
  }
}

Use it as you sorted the primitive types in the previous examples.

// sort using IComparable implemented by User class
Array.Sort(users);  // sort array of User objects

 

https://www.csharp-examples.net/sort-array/