C#属性（Properties）

作者：--    发布时间：2019-11-20

属性(properties)被命名为类，结构和接口的成员。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，并使用相同的语法访问。它们使用访问器，通过这些访问器可以读取，写入或操作私有字段的值。

属性不指定存储位置。它们有读取，写入或计算其值的访问器。

例如，假设有一个名称为student的类，其中包含年龄(age)，名称(name)和代码(code)的私有字段。我们无法从类范围外直接访问这些字段，但是可以拥有访问这些私有字段的属性。

访问器

属性的访问器包含有助于获取(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访问器和set访问器。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;
   }
}

例子

以下示例演示了如何使用属性：

using system;
namespace h3
{
   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 = "10010";
         s.name = "maxsu";
         s.age = 24;
         console.writeline("student info: {0}", s);

         //let us increase age
         s.age += 1;
         console.writeline("student info: {0}", s);
         console.readkey();
      }
   }
}

当上述代码被编译并执行时，它产生以下结果：

student info: code = 10010, name = maxsu, age = 24
student info: code = 10010, name = maxsu, age = 25

抽象属性

抽象类可能有一个抽象属性，它应该在派生类中实现。以下程序说明了这一点：

using system;
namespace h3
{
    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 = "1011";
            s.name = "maxsu";
            s.age = 21;
            console.writeline("student info:- {0}", s);

            //let us increase age
            s.age += 1;
            console.writeline("student info:- {0}", s);
            console.readkey();
        }
    }
}

当上述代码被编译并执行时，它产生以下结果：

student info:- code = 1011, name = maxsu, age = 21
student info:- code = 1011, name = maxsu, age = 22