대화형 모드의 진법(radix) 변환 예제 with Scala

다음은  대화형 모드(interactive mode)에서 진법 변환(radix conversion)하는 Scala 소스 코드이다.
메뉴는 주메뉴 Command: (S)et radix, (A)bout, (Q)uit or E(x)it
와 부메뉴 SubCommand: 'main()' to goto Main menu, 'exit()' or 'quit()' to exit
로 구성되어 있으며, 진법 변환의 핵심은 java.lang.Integer 클래스와 java.lang.Long 클래스의 정적 메소드

         Integer.parseInt(String, int); 
         java.lang.Long.toString(long, int);

울 이용하였으며, 지원되는 진법은 2진법에서 36진법 까지이다. 참고로 Java의 Long 타입과 Scala의 Long 타입은 다르므로, 여기서는 java.lang.Long.toString 처럼 Long 타입의 패키지명을 꼭 붙여야 한다. Scala에는 Integer 타입 대신 Int 타입을 쓰므로 Integer.parseInt는 그대로 써도 된다.

Scala 언어의 try ... catch ... finally ... 구문은

        try {
              블럭
        }
        catch {
             case e1 : 예외타입 =>
                  블럭
             case e2 : 예외타입 =>
                  블럭
        }
        finally {
              블럭
        }

1. /*
2.  *  Filename: convertRadix.scala
3.  *            Convert radix in a interactive mode.
4.  *
5.  *  Execute: scala convertRadix.scala
6.  *
7.  *      Date:  2009/03/09
8.  *    Author:  PH Kim   [ pkim (AT) scripts.pe.kr ]
9.  */
11. import java.io._
12. import java.util._
14. def printUsage() {
15.     println("Usage: scala convertRadix.scala")
16.     println("Convert radix in a interactive mode, where the maximum radix is 36.")
17. }
19. def printAbout() {
20.     println("    About: Convert radix in a interactive mode.")
21. }
23. def printMainMenu() {
24.     println("  Command: (S)et radix, (A)bout, (Q)uit or E(x)it")
25. }
27. def printMainPrompt() {
28.     print("  Prompt> ")
29. }
31. def printSubMenu(srcRadix : Int, destRadix : Int) {
32.     println("    Convert Radix_" + srcRadix + " to Radix_" + destRadix)
33.     println("    SubCommand: 'main()' to goto Main menu, 'exit()' or 'quit()' to exit")
34. }
36. def printSubPrompt() {
37.     print("    Input Value>> ")
38. }
40. def convertRadix(s : String, srcRdx : Int, destRdx : Int) : String = {
41.     var value : Long = 0L
42.     var t = ""
43.     try {
44.         value = Integer.parseInt(s, srcRdx)
45.         t = java.lang.Long.toString(value, destRdx)
46.         return t.toUpperCase()
47.     }
48.     catch {
49.         case e : NumberFormatException =>
50.             println("    Error: " + e.getMessage() + " cantains some invalid character.")
51.             t = "????"
52.             return t
53.     }
54.     finally {
55.       return t.toUpperCase()
56.     }
57. }
59. def doConvert(r : BufferedReader, srcRadix : Int, destRadix : Int) {
60.     var line = ""
61.     var cmd = ""
62.     var srcStr = ""
63.     var destStr = ""
64.     println()
65.     printSubMenu(srcRadix, destRadix)
66.     try {
67.         while (true) {
68.             printSubPrompt()
69.             cmd = r.readLine()
70.             if ("main()".equals(cmd)) {
71.                 return
72.             }
73.             else if ("exit()".equals(cmd) || "quit()".equals(cmd)) {
74.                 System.exit(0)
75.             }
76.             try {
77.                 Integer.parseInt(cmd, srcRadix)
78.                 srcStr = cmd
79.                 destStr = convertRadix(srcStr, srcRadix, destRadix)
80.                 println("        ( " + srcStr + " )_" + srcRadix +  "   --->   ( " + destStr + " )_" + destRadix)
81.                 println()
82.             }
83.             catch {
84.                 case e : NumberFormatException =>
85.                     println("    NumberFormatException: " + e.getMessage())
86.                 case e : IOException =>
87.                     e.printStackTrace()
88.             }
89.         }
90.     }
91. }
93. def doStart() {
94.     var line = ""
95.     var cmd = ""
96.     var srcRadix = 10
97.     var destRadix = 10
98.     var srcStr = ""
99.     var destStr = ""
100.     var onlyOnce : Boolean = true
101.     var r : BufferedReader = new BufferedReader(new InputStreamReader(System.in))
102.     try {
103.         while (true) {
104.             println()
105.             if (onlyOnce) {
106.                 println("  The supported maximum radix is 36.")
107.                 onlyOnce = false
108.             }
109.             printMainMenu()
110.             printMainPrompt()
111.             cmd = r.readLine()
112.             if ("qQxX".contains(cmd) && cmd.length() == 1) {
113.                 System.exit(0)
114.             }
115.             else if ("aA".contains(cmd) && cmd.length() == 1) {
116.                 printAbout()
117.             }
118.             else if ("sS".contains(cmd) && cmd.length() == 1) {
119.                 print("  Input the source and target radices (say, 16 2): ")
120.                 line = r.readLine()
121.                 var st : StringTokenizer = new StringTokenizer(line, " ,\t")
122.                 while (st.countTokens() < 2) {
123.                     print("  Input the source and target radices (say, 16 2): ")
124.                     line = r.readLine()
125.                     st = new StringTokenizer(line, " ,\t");
126.                 }
127.                 srcRadix = Integer.parseInt(st.nextToken())
128.                 destRadix = Integer.parseInt(st.nextToken())
129.                 doConvert(r, srcRadix, destRadix)
130.             }
131.         }
132.     }
133.     catch {
134.         case e: IOException =>
135.             e.printStackTrace()
136.     }
137. }
139. // Begin here
140. if (args.length > 0 && "-h".equals(args(0))) {
141.     printUsage()
142.     System.exit(1)
143. }
145. doStart()

실행> scala convertRadix.scala

  The supported maximum radix is 36.
  Command: (S)et radix, (A)bout, (Q)uit or E(x)it
  Prompt> s
  Input the source and target radices (say, 16 2): 16 2

    Convert Radix_16 to Radix_2
    SubCommand: 'main()' to goto Main menu, 'exit()' or 'quit()' to exit
    Input Value>> 1FF
        ( 1FF )_16   --->   ( 111111111 )_2

    Input Value>> main()

  Command: (S)et radix, (A)bout, (Q)uit or E(x)it
  Prompt> S
  Input the source and target radices (say, 16 2): 2 8

    Convert Radix_2 to Radix_8
    SubCommand: 'main()' to goto Main menu, 'exit()' or 'quit()' to exit
    Input Value>> 1011001
        ( 1011001 )_2   --->   ( 131 )_8

    Input Value>> main()

  Command: (S)et radix, (A)bout, (Q)uit or E(x)it
  Prompt> x





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