C #: learning the Params keyword

I saw Params today. I learned it without having used it before.

The Params keyword has the following features:

• The Params keyword can be used to specify a variable number of parameters (the number of parameters is not specified ).
• You can send a comma-separated list of parameters of the specified type in the parameter declaration or a parameter array of the specified type.
• You can leave the parameter unspecified.
• After the Params keyword in the method declaration, no other parameters are allowed, and only one Params keyword is allowed in the method declaration.

 

View code

 1 using system;
2 using system. Collections. Generic;
3 using system. LINQ;
4 using system. text;
5
6 namespace consoleapplication5
7 {
8. Public class myclass
9 {
10 public static void useparams (Params int [] list)
11 {
12 For (INT I = 0; I <list. length; I ++ ){
13 console. Write (list [I] + "");
14}
15 console. writeline ();
16}
17
18 public static void useparams2 (Params object [] list)
19 {
20 For (INT I = 0; I <list. length; I ++ ){
21 console. Write (list [I] + "");
22}
23 console. writeline ();
24}
25
26 static void main ()
27 {
28 // you can send a comma-separated list of arguments of the specified type.
29 // you can use a comma-separated sequence parameter to specify the type.
30 useparams (1, 2, 3, 4 );
31 useparams2 (1, 'A', "test ");
32
33 // A Params parameter accepts zero or more arguments.
34 // One Params parameter accepts zero or multiple parameters.
35 // The following calling statement displays only a blank line.
36 // The statement below shows only one blank line.
37 useparams2 ();
38
39 // an array argument can be passed, as long as the Array
40 // type matches the parameter type of the method being called.
41 // as long as the array type conforms to the parameter type of the method, it can be called
42 int [] myintarray = {5, 6, 7, 8, 9 };
43 useparams (myintarray );
44
45 object [] myobjarray = {2, 'B', "test", "again "};
46 useparams2 (myobjarray );
47
48 // The following call causes a compiler error because the object
49 // array cannot be converted into an integer array.
50 // useparams (myobjarray );
51
52 // The following call does not cause an error, but the entire
53 // integer array becomes the first element of the Params array.
54 useparams2 (myintarray );
55}
56}
57}
58

In fact, the usage of the Params keyword is quite flexible! You can try it later!

(This article references msdn: http://msdn.microsoft.com/zh-cn/library/w5zay9db (V = vs.100). aspx)