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部分內容來自MSDN

implicit 關鍵字用于聲明隱式的用戶定(ding)義類(lei)(lei)型(xing)(xing)轉換(huan)運算符。如果轉換(huan)過程可(ke)以確(que)保不會造成(cheng)數據(ju)丟失，則可(ke)使用該關鍵字在用戶定(ding)義類(lei)(lei)型(xing)(xing)和其他類(lei)(lei)型(xing)(xing)之間進行(xing)隱式轉換(huan)。

 1     class Digit
 2 
 3     {
 4 
 5         public Digit(double d) { val = d; }
 6 
 7         public double val;
 8 
 9  
10 
11  
12 
13         // User-defined conversion from Digit to double
14 
15         public static implicit operator double(Digit d)
16 
17         {
18 
19             return d.val;
20 
21         }
22 
23         //  User-defined conversion from double to Digit
24 
25         public static implicit operator Digit(double d)
26 
27         {
28 
29             return new Digit(d);
30 
31         }
32 
33     }
34 
35     class Program
36 
37     {
38 
39         static void Main(string[] args)
40 
41         {
42 
43             Digit dig = new Digit(7);
44 
45             //This call invokes the implicit "double" operator
46 
47             double num = dig;
48 
49             //This call invokes the implicit "Digit" operator
50 
51             Digit dig2 = 12;
52 
53             Console.WriteLine("num = {0} dig2 = {1}", num, dig2.val);
54 
55             Console.ReadLine();
56 
57         }
58 
59     }

explicit 關鍵字用于聲明必須使用強制轉換來調用的(de)用戶定義(yi)的(de)類(lei)型轉換運算(suan)符

 1 // cs_keyword_explicit_temp.cs
 2 using System;
 3 class Celsius
 4 {
 5     public Celsius(float temp)
 6     {
 7         degrees = temp;
 8     }
 9     public static explicit operator Fahrenheit(Celsius c)
10     {
11         return new Fahrenheit((9.0f / 5.0f) * c.degrees + 32);
12     }
13     public float Degrees
14     {
15         get { return degrees; }
16     }
17     private float degrees;
18 }
19 
20 class Fahrenheit
21 {
22     public Fahrenheit(float temp)
23     {
24         degrees = temp;
25     }
26     public static explicit operator Celsius(Fahrenheit f)
27     {
28         return new Celsius((5.0f / 9.0f) * (f.degrees - 32));
29     }
30     public float Degrees
31     {
32         get { return degrees; }
33     }
34     private float degrees;
35 }
36 
37 class MainClass
38 {
39     static void Main()
40     {
41         Fahrenheit f = new Fahrenheit(100.0f);
42         Console.Write("{0} fahrenheit", f.Degrees);
43         Celsius c = (Celsius)f;
44         Console.Write(" = {0} celsius", c.Degrees);
45         Fahrenheit f2 = (Fahrenheit)c;
46         Console.WriteLine(" = {0} fahrenheit", f2.Degrees);
47     }
48 }

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