C# - 属性

属性是类、结构和接口的命名成员。类或结构中的成员变量或方法称为字段。属性是字段的扩展，并且使用相同的语法进行访问。它们使用访问器，通过访问器可以读取、写入或操作私有字段的值。

属性不会命名存储位置。相反，它们具有访问器来读取、写入或计算其值。

例如，让我们有一个名为 Student 的类，其中包含年龄、姓名和代码的私有字段。我们无法从类范围之外直接访问这些字段，但我们可以使用属性来访问这些私有字段。

访问器

属性的访问器包含帮助获取（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 get 访问器、set 访问器或两者兼而有之。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;
   }
}

示例

以下示例演示了属性的使用 -

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();
      }
   }
}

当以上代码编译并执行时，会产生以下结果 -

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

抽象属性

抽象类可能具有抽象属性，该属性应在派生类中实现。以下程序说明了这一点 -

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();
      }
   }
}

当以上代码编译并执行时，会产生以下结果 -

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