C#学习笔记四: C#3.0自动属性&匿名属性及扩展方法

 1 class Person
 2 {
 3     //定义私有字段
 4     private string name;
 5 
 6     //定义可读写属性
 7     public string Name
 8     {
 9         get{return name;}
10         set{name = value;}
11     }
12 
13     private int age;
14     //定义只读属性
15     public int Age
16     {
17         get{return age;}
18     }
19 }

1 class Person
2 {
3     //使用自动实现的属性来定义属性
4     //定义可读写属性
5     public string Name{get; set;}
6     //定义只读属性
7     public int Age{get; private set;}
8 }

 1 public struct TestPerson
 2 {
 3     public string Name { get; set; }
 4     public int Age { get; private set; }
 5 
 6     //结构体中, 不显式地调用无参构造函数this()时, 会出现编译时错误
 7     public TestPerson(string name)
 8     : this()
 9     {
10         this.Name = name;
11     }
12 }

1 class Program
2 {
3     static void Main(stirng[] args)
4     {
5         //用var声明局部变量
6         var stringValue = "Barry Wang";
7         stringValue = 2;
8     }
9 }

 1 class Program
 2 {
 3     static void Main(string[] args)
 4     { 
 5         //没有对象初始化器时的代码
 6         Person p = new Person("BarryWang", 25);
 7         p.Weight = 60;
 8         p.Height = 170;
 9     }
10 }
11 
12 public class Person
13 {
14     public string Name { get; set; }
15     public int Age { get; set; }
16     public int Weight { get; set; }
17     public int Height { get; set; }
18 
19     //定义不同情况下的初始化函数
20     public Person() { }
21     public Person(string name) { } 
22     public Person(string name, int age) { }
23     public Person(string name, int age, int weight) { }
24     public Person(string name, int age, int weight, int height) 
25     {
26         this.Name = name;
27         this.Age = age;
28         this.Weight = weight;
29         this.Height = height;
30     }
31 }

 1 class Program
 2 {
 3     static void Main(string[] args)
 4     {
 5         //使用对象初始化器初始化
 6         Person p = new Person() {Name = "Barry Wang", Age = 25, Weght = 60, Height = 70};
 7         //下面这行代码和上面一行是等价的, 只不过下面省略了构造函数的圆括号而已
 8         Person p2 = new Person {Name = "Barry Wang", Age = 25, Weght = 60, Height = 70};
 9     }
10 }
11 
12 public class Person
13 {
14     public string Name { get; set; }
15     public int Age { get; set; }
16     public int Weight { get; set; }
17     public int Height { get; set; }
18 }

1 class Program
2 {
3     List<string> newNames = new List<string>
4     {
5         "A", "B", "C"
6     };
7 }

 1 class Program
 2 {
 3     static void Main(string[] args)
 4     { 
 5         //定义匿名类型对象
 6         var person = new {Name = "Barry Wang", Age = 25 };
 7         Console.WriteLine("{0} 的年龄为: {1}", person.Name, person.Age);
 8 
 9         //定义匿名类型数组
10         var personCollection = new[]
11         {
12             new {Name = "Barry", Age = 30},
13             new {Name = "Brad", Age = 22},
14             new {Name = "Tony", Age = 25}
15         };
16 
17         int totalAge = 0;
18         foreach (var p in personCollection)
19         {
20             //下面一行代码证明了Age属性时int类型
21             totalAge += p.Age;
22         }
23 
24         Console.WriteLine("所有人的年龄总和为: {0}", totalAge);
25         Console.ReadKey();
26     }
27 }

 1 public static class Extensions
 2 {
 3     //对string 类扩展，注意this关键字
 4     public static void TestStr(this string s)
 5     {
 6         Console.WriteLine(s.ToString());
 7     }
 8     //对int 类扩展
 9     public static void TestInt(this int i, string s)
10     {
11         Console.WriteLine(s + i.ToString());
12     }
13 }
14 class Program
15 {
16     static void Main(string[] args)
17     {
18         //使用扩展方法
19         string s = "Test Extensions Methods";
20         s.TestStr();//调用方法1
21         Extensions.TestStr(s);//调用方法2
22         int i = 100;
23         i.TestInt("This value is ");
24         Extensions.TestInt(i, "This value is ");
25         Console.ReadKey();
26     }
27 }

 1 namespace CurrentNameSpace
 2 {
 3     //要想使用不用命名空间下的扩展方法, 需要先引入该命名空间
 4     using CustomNameSpace;
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9             Person p = new Person {Name = "BarryWang"};
10             p.Print();//等价于==>ExtensionClass.Print(p);
11             p.Print("Hello");
12             Console.ReadKey();
13         }
14     }
15 
16     //自定义类型
17     public class Person
18     {
19         public string Name { get; set; }
20     }
21 
22     //当前命名空间下的扩展方法定义
23     public static class ExtensionClass
24     {
25         public static void Print(this Person p)
26         {
27             Console.WriteLine("调用的是当前命名空间下的扩展方法输出, 姓名为: {0}", p.Name);
28         }
29     }
30 }
31 
32 namespace CustomNameSpace
33 {
34     using CurrentNameSpace;
35     public static class CustomExtensionClass
36     {
37         //扩展方法定义
38         public static void Pint(this Person p)
39         {
40             Console.WriteLine("调用的是CustomNameSpace命名空间下扩展方法输出: 姓名为: {0}", p.Name);
41         }
42 
43         //扩展方法定义
44         public static void Pint(this Person p, string s)
45         {
46             Console.WriteLine("调用的是CustomNameSpace命名空间下扩展方法输出: 姓名为: {0},附加字符串为{1}", p.Name, s);
47         }
48     }
49 }