[C#] 一文速通C#

1
using System; // 使用 System 命名空間
2
namespace HelloApplication
3
{
4
    class HelloWorld
5
    {
6
        static void Main(string[] args)
7
        {
8
            Console.WriteLine("Hello, world.");
9
        }
10
    }
11
}

1
string str = @"\t\n\\";
2
Console.WriteLine(str);
3
/* 結果：\t\n\\ */

1
string str = @"<script type=""text/javascript"">
2
    <!--
3
    -->
4
</script>";

1
byte a = 1;
2
int b = a; // 發生隱形轉換

1
foreach(item in <variables>) {
2
    ...
3
}

1
// 宣告
2
int ChangeA(int a)
3
{
4
    a ++;
5
    return a;
6
}
7

8
...
9

10
// 呼叫
11
int a = 4;
12
int b = ChangeA(a);
13
Console.WriteLine(a);
14
Console.WriteLine(b);
15
// a 輸出 4，b 輸出 5

1
// 宣告
2
int ChangeA(ref int a)
3
{
4
    a ++;
5
    return a;
6
}
7

8
...
9

10
// 呼叫
11
int a = 4;
12
int b = ChangeA(ref a);
13
Console.WriteLine(a);
14
Console.WriteLine(b);
15
// a 輸出 5，b 輸出 5

1
// 宣告
2
void ChangeA(out int a)
3
{
4
    a ++;
5
}
6

7
...
8

9
// 呼叫
10
int a = 4;
11
ChangeA(out a);
12
Console.WriteLine(a);
13
// a 輸出 5

1
int? num = 1;
2
int? num_2 = null;

1
int? num = 1;
2
int? num_2 = null;
3

4
int num_3 = num ?? 10; // num 不為空，則 num_3 優先取原值，num_3 = 1
5
int num_4 = num_2 ?? 10; // num_2 為空，則 num_4 會取預設值，num_4 = 10

1
int ChangeA(params int[] a)
2
{
3
    ...
4
}

1
// 宣告
2
struct Books
3
{
4
    public string title;
5
    public string author;
6
    public string subject;
7
    public int book_id;
8
}
9

10
...
11

12
// 使用
13
Books book_1; // 無需使用new

1
class Book() {
2
    ...
3
    ~Book()
4
    {
5
        Console.WriteLine("物件被銷毀。");
6
    }
7
    ...
8
}

1
class Parent
2
{
3
    public virtual void sayHello()
4
    {
5
        Console.WriteLine("Hello, parent!");
6
    }
7
}
8

9
class Son : Parent
10
{
11
    public override void sayHello() {
12
        Console.log("Hello, son!");
13
    }
14
}

1
using System;
2
namespace PolymorphismApplication
3
{
4
    public class TestData
5
    {
6
        public int Add(int a, int b, int c)
7
        {
8
            return a + b + c;
9
        }
10
        public int Add(int a, int b)
11
        {
12
            return a + b;
13
        }
14
    }
15
    class Program
16
    {
17
        static void Main(string[] args)
18
        {
19
            TestData dataClass = new TestData();
20
            int add1 = dataClass.Add(1, 2);
21
            int add2 = dataClass.Add(1, 2, 3);
22

23
            Console.WriteLine("add1 :" + add1);
24
            Console.WriteLine("add2 :" + add2);
25
        }
26
    }
27
}

1
public static Box operator+ (Box b, Box c)
2
{
3
   Box box = new Box();
4
   box.length = b.length + c.length;
5
   box.breadth = b.breadth + c.breadth;
6
   box.height = b.height + c.height;
7
   return box;
8
}

1
public class Shape
2
{
3
    public int X { get; private set; }
4
    public int Y { get; private set; }
5
    public int Height { get; set; }
6
    public int Width { get; set; }
7

8
    // Virtual function
9
    public virtual void Draw()
10
    {
11
        Console.WriteLine("Start drawing...");
12
    }
13
}

1
namespace namespace_name
2
{
3
   ...
4
}

1
namespace_name.item_name;

1
Console.WriteLine ("Hello there");

1
System.Console.WriteLine("Hello there");

1
using System;
2
using SomeNameSpace;
3
using SomeNameSpace.Nested;
4

5
namespace SomeNameSpace
6
{
7
    public class MyClass
8
    {
9
        static void Main()
10
        {
11
            Console.WriteLine("In SomeNameSpace");
12
            Nested.NestedNameSpaceClass.SayHello();
13
        }
14
    }
15

16
    // Nested namespace
17
    namespace Nested
18
    {
19
        public class NestedNameSpaceClass
20
        {
21
            public static void SayHello()
22
            {
23
                Console.WriteLine("In Nested");
24
            }
25
        }
26
    }
27
}

1
#define RELEASE

1
#define PI
2
using System;
3
namespace PreprocessorDAppl
4
{
5
   class Program
6
   {
7
      static void Main(string[] args)
8
      {
9
         #if (PI)
10
            Console.WriteLine("PI is defined");
11
         #else
12
            Console.WriteLine("PI is not defined");
13
         #endif
14
         Console.ReadKey();
15
      }
16
   }
17
}

1
FileStream <object_name> = new FileStream( <file_name>,
2
<FileMode Enumerator>, <FileAccess Enumerator>, <FileShare Enumerator>);

1
FileStream F = new FileStream("sample.txt", FileMode.Open, FileAccess.Read, FileShare.Read);

1
[Obsolete(
2
   message,
3
   iserror
4
)]

1
using System;
2
public class MyClass
3
{
4
   [Obsolete("Don't use OldMethod, use NewMethod instead", true)]
5
   static void OldMethod()
6
   {
7
      Console.WriteLine("It is the old method");
8
   }
9
   static void NewMethod()
10
   {
11
      Console.WriteLine("It is the new method");
12
   }
13
   public static void Main()
14
   {
15
      OldMethod();
16
   }
17
}

1
[Conditional(
2
   conditionalSymbol
3
)]

1
#define DEBUG
2
using System;
3
using System.Diagnostics;
4
public class Myclass
5
{
6
    [Conditional("DEBUG")]
7
    public static void Message(string msg)
8
    {
9
        Console.WriteLine(msg);
10
    }
11
}
12
class Test
13
{
14
    static void function1()
15
    {
16
        Myclass.Message("In Function 1.");
17
        function2();
18
    }
19
    static void function2()
20
    {
21
        Myclass.Message("In Function 2.");
22
    }
23
    public static void Main()
24
    {
25
        Myclass.Message("In Main function.");
26
        function1();
27
        Console.ReadKey();
28
    }
29
}

1
[AttributeUsage(
2
   validon,
3
   AllowMultiple=allowmultiple,
4
   Inherited=inherited
5
)]

1
[AttributeUsage(AttributeTargets.Class |
2
AttributeTargets.Constructor |
3
AttributeTargets.Field |
4
AttributeTargets.Method |
5
AttributeTargets.Property,
6
AllowMultiple = true)]
7

8
public class DeBugInfo : System.Attribute

1
[AttributeUsage(AttributeTargets.Class |
2
AttributeTargets.Constructor |
3
AttributeTargets.Field |
4
AttributeTargets.Method |
5
AttributeTargets.Property,
6
AllowMultiple = true)]
7

8
public class DeBugInfo : System.Attribute
9
{
10
  private int bugNo;
11
  private string developer;
12
  private string lastReview;
13
  public string message;
14

15
  public DeBugInfo(int bg, string dev, string d)
16
  {
17
      this.bugNo = bg;
18
      this.developer = dev;
19
      this.lastReview = d;
20
  }
21

22
  public int BugNo
23
  {
24
      get
25
      {
26
          return bugNo;
27
      }
28
  }
29
  public string Developer
30
  {
31
      get
32
      {
33
          return developer;
34
      }
35
  }
36
  public string LastReview
37
  {
38
      get
39
      {
40
          return lastReview;
41
      }
42
  }
43
  public string Message
44
  {
45
      get
46
      {
47
          return message;
48
      }
49
      set
50
      {
51
          message = value;
52
      }
53
  }
54
}

1
[DeBugInfo(45, "Zara Ali", "12/8/2012", Message = "Return type mismatch")]
2
[DeBugInfo(49, "Nuha Ali", "10/10/2012", Message = "Unused variable")]
3
class Rectangle
4
{
5
  protected double length;
6
  protected double width;
7
  public Rectangle(double l, double w)
8
  {
9
      length = l;
10
      width = w;
11
  }
12
  [DeBugInfo(55, "Zara Ali", "19/10/2012",
13
  Message = "Return type mismatch")]
14
  public double GetArea()
15
  {
16
      return length * width;
17
  }
18
  [DeBugInfo(56, "Zara Ali", "19/10/2012")]
19
  public void Display()
20
  {
21
      Console.WriteLine("Length: {0}", length);
22
      Console.WriteLine("Width: {0}", width);
23
      Console.WriteLine("Area: {0}", GetArea());
24
  }
25
}

1
using System;
2
using System.Reflection;
3
namespace BugFixApplication
4
{
5
   [AttributeUsage(AttributeTargets.Class |
6
   AttributeTargets.Constructor |
7
   AttributeTargets.Field |
8
   AttributeTargets.Method |
9
   AttributeTargets.Property,
10
   AllowMultiple = true)]
11

12
   public class DeBugInfo : System.Attribute
13
   {
14
      private int bugNo;
15
      private string developer;
16
      private string lastReview;
17
      public string message;
18

19
      public DeBugInfo(int bg, string dev, string d)
20
      {
21
         this.bugNo = bg;
22
         this.developer = dev;
23
         this.lastReview = d;
24
      }
25

26
      public int BugNo
27
      {
28
         get
29
         {
30
            return bugNo;
31
         }
32
      }
33
      public string Developer
34
      {
35
         get
36
         {
37
            return developer;
38
         }
39
      }
40
      public string LastReview
41
      {
42
         get
43
         {
44
            return lastReview;
45
         }
46
      }
47
      public string Message
48
      {
49
         get
50
         {
51
            return message;
52
         }
53
         set
54
         {
55
            message = value;
56
         }
57
      }
58
   }
59
   [DeBugInfo(45, "Zara Ali", "12/8/2012",
60
        Message = "Return type mismatch")]
61
   [DeBugInfo(49, "Nuha Ali", "10/10/2012",
62
        Message = "Unused variable")]
63
   class Rectangle
64
   {
65
      protected double length;
66
      protected double width;
67
      public Rectangle(double l, double w)
68
      {
69
         length = l;
70
         width = w;
71
      }
72
      [DeBugInfo(55, "Zara Ali", "19/10/2012",
73
           Message = "Return type mismatch")]
74
      public double GetArea()
75
      {
76
         return length * width;
77
      }
78
      [DeBugInfo(56, "Zara Ali", "19/10/2012")]
79
      public void Display()
80
      {
81
         Console.WriteLine("Length: {0}", length);
82
         Console.WriteLine("Width: {0}", width);
83
         Console.WriteLine("Area: {0}", GetArea());
84
      }
85
   }//end class Rectangle
86

87
   class ExecuteRectangle
88
   {
89
      static void Main(string[] args)
90
      {
91
         Rectangle r = new Rectangle(4.5, 7.5);
92
         r.Display();
93
         Type type = typeof(Rectangle);
94

95
         foreach (Object attributes in type.GetCustomAttributes(false))
96
         {
97
            DeBugInfo dbi = (DeBugInfo)attributes;
98
            if (null != dbi)
99
            {
100
               Console.WriteLine("Bug no: {0}", dbi.BugNo);
101
               Console.WriteLine("Developer: {0}", dbi.Developer);
102
               Console.WriteLine("Last Reviewed: {0}",
103
                                        dbi.LastReview);
104
               Console.WriteLine("Remarks: {0}", dbi.Message);
105
            }
106
         }
107

108
         foreach (MethodInfo m in type.GetMethods())
109
         {
110
            foreach (Attribute a in m.GetCustomAttributes(true))
111
            {
112
               DeBugInfo dbi = (DeBugInfo)a;
113
               if (null != dbi)
114
               {
115
                  Console.WriteLine("Bug no: {0}, for Method: {1}",
116
                                                dbi.BugNo, m.Name);
117
                  Console.WriteLine("Developer: {0}", dbi.Developer);
118
                  Console.WriteLine("Last Reviewed: {0}",
119
                                                dbi.LastReview);
120
                  Console.WriteLine("Remarks: {0}", dbi.Message);
121
               }
122
            }
123
         }
124
         Console.ReadLine();
125
      }
126
   }
127
}

1
public string Code
2
{
3
   get
4
   {
5
      return code;
6
   }
7
   set
8
   {
9
      code = value;
10
   }
11
}
12

13
public string Name
14
{
15
   get
16
   {
17
     return name;
18
   }
19
   set
20
   {
21
     name = value;
22
   }
23
}
24

25
public int Age
26
{
27
   get
28
   {
29
      return age;
30
   }
31
   set
32
   {
33
      age = value;
34
   }
35
}

1
using System;
2
namespace mynamespace
3
{
4
   public abstract class Person
5
   {
6
      public abstract string Name
7
      {
8
         get;
9
         set;
10
      }
11
      public abstract int Age
12
      {
13
         get;
14
         set;
15
      }
16
   }
17
   class Student : Person
18
   {
19

20
      private string code = "N.A";
21
      private string name = "N.A";
22
      private int age = 0;
23

24
      public string Code
25
      {
26
         get
27
         {
28
            return code;
29
         }
30
         set
31
         {
32
            code = value;
33
         }
34
      }
35

36
      public override string Name
37
      {
38
         get
39
         {
40
            return name;
41
         }
42
         set
43
         {
44
            name = value;
45
         }
46
      }
47

48
      public override int Age
49
      {
50
         get
51
         {
52
            return age;
53
         }
54
         set
55
         {
56
            age = value;
57
         }
58
      }
59
      public override string ToString()
60
      {
61
         return "Code = " + Code +", Name = " + Name + ", Age = " + Age;
62
      }
63
   }
64
   class ExampleDemo
65
   {
66
      public static void Main()
67
      {
68
         Student s = new Student();
69

70
         s.Code = "001";
71
         s.Name = "Zara";
72
         s.Age = 9;
73
         Console.WriteLine("Student Info:- {0}", s);
74
         s.Age += 1;
75
         Console.WriteLine("Student Info:- {0}", s);
76
         Console.ReadKey();
77
       }
78
   }
79
}

1
public delegate int MyDelegate (string s);

1
using System;
2

3
delegate int NumberChanger(int n);
4
namespace DelegateAppl
5
{
6
   class TestDelegate
7
   {
8
      static int num = 10;
9
      public static int AddNum(int p)
10
      {
11
         num += p;
12
         return num;
13
      }
14

15
      public static int MultNum(int q)
16
      {
17
         num *= q;
18
         return num;
19
      }
20
      public static int getNum()
21
      {
22
         return num;
23
      }
24

25
      static void Main(string[] args)
26
      {
27
         NumberChanger nc1 = new NumberChanger(AddNum);
28
         NumberChanger nc2 = new NumberChanger(MultNum);
29

30
         nc1(25);
31
         Console.WriteLine("Value of Num: {0}", getNum());
32
         nc2(5);
33
         Console.WriteLine("Value of Num: {0}", getNum());
34
         Console.ReadKey();
35
      }
36
   }
37
}

1
using System;
2

3
delegate int NumberChanger(int n);
4
namespace DelegateAppl
5
{
6
   class TestDelegate
7
   {
8
      static int num = 10;
9
      public static int AddNum(int p)
10
      {
11
         num += p;
12
         return num;
13
      }
14

15
      public static int MultNum(int q)
16
      {
17
         num *= q;
18
         return num;
19
      }
20
      public static int getNum()
21
      {
22
         return num;
23
      }
24

25
      static void Main(string[] args)
26
      {
27
         NumberChanger nc;
28
         NumberChanger nc1 = new NumberChanger(AddNum);
29
         NumberChanger nc2 = new NumberChanger(MultNum);
30
         nc = nc1;
31
         nc += nc2;
32

33
         nc(5);
34
         Console.WriteLine("Value of Num: {0}", getNum());
35
         Console.ReadKey();
36
      }
37
   }
38
}

1
// 創建一個委託
2
public delegate void DelSendMsg(string msg);
3

4
// 事件發布器
5
class Publisher
6
{
7
    // 創建一個事件，事件實際上是一個特殊的委託物件
8
    public event DelSendMsg sendEvent;
9

10
    // 發布器的 publish 方法
11
    public void sendMsg(string msg)
12
    {
13
        // 如果訂閱器訂閱了該事件
14
        if(sendEvent != null)
15
        {
16
            // 執行事件，具體實現由訂閱器的實作函式來實作
17
            sendEvent(msg);
18
        }
19
    }
20
}
21

22
// 訂閱器
23
class Subscriber {
24
    // 訂閱方法
25
    public void subscribe(Publisher publisher) {
26

27
        // 註冊事件處理函式
28
        publisher.sendEvent += new DelSendMsg(publisherSendEvent);
29

30
        // 定義事件處理函式
31
        void publisherSendEvent(string msg)
32
        {
33
            Console.WriteLine("接收到訊息：{0}", msg);
34
        }
35
    }
36
}
37

38
class Hello
39
{
40
    static void Main(string[] args)
41
    {
42
        Publisher publisher = new Publisher();
43

44
        Subscriber subscriber = new Subscriber();
45

46
        // 註冊
47
        subscriber.subscribe(publisher);
48

49
        // 測試呼叫 sendMsg 方法
50
        publisher.sendMsg("發送訊息測試。");
51
    }
52
}