Csharp 简明教程

C

Properties 是类、结构和接口的已命名成员。类或结构中的成员变量或方法称为 Fields 。属性是字段的扩展，并使用相同的语法访问。它们使用 accessors ，可以通过它来读取、写入或操作私有字段的值。

属性不命名存储位置。相反，它们有 accessors 来读取、写入或计算它们的值。

例如，让我们有一个名为 Student 的类，其中有 age、name 和 code 的私有字段。我们不能直接从类范围之外访问这些字段，但我们可以有属性来访问这些私有字段。

Accessors

属性的 accessor 包含可帮助获取（读取或计算）或设置（写入）属性的可执行语句。访问器声明可以包含一个获取访问器、一个设置访问器或两者。例如 −

// Declare a Code property of type string:
public string Code {
   get {
      return code;
   }
   set {
      code = value;
   }
}

// Declare a Name property of type string:
public string Name {
   get {
      return name;
   }
   set {
      name = value;
   }
}

// Declare a Age property of type int:
public int Age {
   get {
      return age;
   }
   set {
      age = value;
   }
}

Example

以下示例演示了属性的用法 −

using System;
namespace tutorialspoint {
   class Student {
      private string code = "N.A";
      private string name = "not known";
      private int age = 0;

      // Declare a Code property of type string:
      public string Code {
         get {
            return code;
         }
         set {
            code = value;
         }
      }

      // Declare a Name property of type string:
      public string Name {
         get {
            return name;
         }
         set {
            name = value;
         }
      }

      // Declare a Age property of type int:
      public int Age {
         get {
            return age;
         }
         set {
            age = value;
         }
      }
      public override string ToString() {
         return "Code = " + Code +", Name = " + Name + ", Age = " + Age;
      }
   }

   class ExampleDemo {
      public static void Main() {

         // Create a new Student object:
         Student s = new Student();

         // Setting code, name and the age of the student
         s.Code = "001";
         s.Name = "Zara";
         s.Age = 9;
         Console.WriteLine("Student Info: {0}", s);

         //let us increase age
         s.Age += 1;
         Console.WriteLine("Student Info: {0}", s);
         Console.ReadKey();
      }
   }
}

编译并执行上述代码后，将产生以下结果 −

Student Info: Code = 001, Name = Zara, Age = 9
Student Info: Code = 001, Name = Zara, Age = 10

Abstract Properties

一个抽象类可能有一个抽象属性，该属性应在派生类中实现。以下程序对此进行了说明 −

using System;

namespace tutorialspoint {
   public abstract class Person {
      public abstract string Name {
         get;
         set;
      }
      public abstract int Age {
         get;
         set;
      }
   }
   class Student : Person {
      private string code = "N.A";
      private string name = "N.A";
      private int age = 0;

      // Declare a Code property of type string:
      public string Code {
         get {
            return code;
         }
         set {
            code = value;
         }
      }

      // Declare a Name property of type string:
      public override string Name {
         get {
            return name;
         }
         set {
            name = value;
         }
      }

      // Declare a Age property of type int:
      public override int Age {
         get {
            return age;
         }
         set {
            age = value;
         }
      }
      public override string ToString() {
         return "Code = " + Code +", Name = " + Name + ", Age = " + Age;
      }
   }

   class ExampleDemo {
      public static void Main() {
         // Create a new Student object:
         Student s = new Student();

         // Setting code, name and the age of the student
         s.Code = "001";
         s.Name = "Zara";
         s.Age = 9;
         Console.WriteLine("Student Info:- {0}", s);

         //let us increase age
         s.Age += 1;
         Console.WriteLine("Student Info:- {0}", s);
         Console.ReadKey();
      }
   }
}

编译并执行上述代码后，将产生以下结果 −

Student Info: Code = 001, Name = Zara, Age = 9
Student Info: Code = 001, Name = Zara, Age = 10