진법(radix) 표 만들기 예제 with F#

컴퓨터 프로그래밍에서 꼭 알아두어야 할 주요 진법은 당연히 10진법, 2진법, 8진법, 16진법이다.
다음은  0 에서 15 까지의 정수를 10진법, 2진법, 8진법, 16진법의 표로 만들어 보여주는 F# 소스 코드이다. 진법 변환에 필요한 함수

        atoi(string, radix)
        itoa(number, radix)

를 F# 코드로 자체 작성하여 사용하였다.

(아래의 소스는 Python 소스를 F# 소스로 일대일 변환 수정한 것이라서, F# 언어의 명령형 언어 특징을 위주로 작성되어 있다.)

1. (*
2.  *  Filename: MakeRadixTable.fs
3.  *            Show the radix table with 10-, 2-, 8-, 16-radices.
4.  *
5.  *  Compile: fsc MakeRadixTable.fs
6.  *  Execute: MakeRadixTable
7.  *
8.  *      Date:  2010/07/15
9.  *    Author:  PH Kim   [ pkim (AT) scripts.pe.kr ]
10.  *)
12. #light
14. exception RuntimeError of string
15. exception ValueError of string
17. let BASE36 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
19. let println s =
20.     printfn "%O" s
22. let print s =
23.     printf "%O" s
25. let printUsage dummy =
26.     println "Usage: MakeRadixTable"
27.     println "Show the radix table with 10-, 2-, 8-, 16-radices."
29. let itoa (num : int, radix : int) =
30.    let mutable isNegative = false
31.    let mutable numx = num
32.    if num < 0 then
33.       isNegative <- true
34.       numx <- (-num)
36.    let mutable arr = [  ]
37.    let mutable q = numx
38.    let mutable r = 0
39.    while (q >= radix) do
40.        r <- int (q % radix)
41.        q <- int (q / radix)
42.        arr <- List.append arr [ sprintf "%O" (BASE36.[r]) ]
44.    arr <- List.append arr [ sprintf "%O" (BASE36.[q]) ]
45.    if isNegative then
46.       arr <- List.append arr [ "-" ]
47.    arr <- List.rev arr
49.    System.String.Join("", List.toArray arr)
52. let atoi (s : string, radix : int) : int =
53.     let mutable ret = 0
54.     let mutable isNegative = false
55.     let len = s.Length
56.     let mutable valx = 0
57.     let mutable c = s.[0]
59.     if c = '-' then
60.         isNegative <- true
61.     elif (c >= '0' && c <= '9') then
62.         ret <- (int c) - (int '0')
63.     elif (c >= 'A' && c <= 'Z') then
64.         ret <- int c - int 'A' + 10
65.     elif (c >= 'a' && c <= 'z') then
66.         ret <- int c - int 'a' + 10
68.     if (ret >= radix) then
69.         printfn "    Error: Can not read \"%s\" (as radix %d): %O is an invalid character!" s radix ret
71.     for i = 1 to len - 1 do
72.         c <- s.[i]
73.         ret <- ret*radix
74.         if (c >= '0' && c <= '9') then
75.             valx <- int c - int '0'
76.         elif (c >= 'A' && c <= 'Z') then
77.             valx <- int c - int 'A' + 10
78.         elif (c >= 'a' && c <= 'z') then
79.             valx <- int c - int 'a' + 10
81.         if (valx >= radix) then
82.             printfn "    Error: Can not read \"%s\" (as radix %d): %O is an invalid character!" s radix c
84.         ret <- ret + valx
86.     if (isNegative) then
87.         ret <- (-ret )
89.     ret
91. let makeTable dummy =
92.     let mutable sbuf = ""
93.     let mutable abuf = ""
94.     let mutable tbuf = ""
96.     for i in 0..(4-1) do
97.         sbuf <- sbuf + "+-------"
98.     sbuf <- sbuf + "+"
99.     println(sbuf)
101.     sbuf <- "|  Dec"
102.     sbuf <- sbuf +  "\t|   Bin"
103.     sbuf <- sbuf +  "\t|  Oct"
104.     sbuf <- sbuf +  "\t|  Hex  |"
105.     println(sbuf)
107.     sbuf <- ""
108.     for i in 0..(4-1) do
109.         sbuf <- sbuf +  "+-------"
110.     sbuf <- sbuf +  "+"
111.     println(sbuf)
113.     for i in 0..(16-1) do
114.         sbuf <- sprintf "|   %2d" i
115.         abuf <- itoa(i, 2)
116.         tbuf <- sprintf "\t|  %4s" abuf
117.         sbuf <- sbuf +  tbuf
119.         abuf <- itoa(i, 8)
120.         tbuf <- sprintf "\t|   %2s" abuf
121.         sbuf <- sbuf + tbuf
123.         abuf <- itoa(i, 16)
124.         tbuf <- sprintf "\t|    %-2s |"  abuf
125.         sbuf <- sbuf +  tbuf
126.         println(sbuf)
128.     sbuf <- ""
129.     for i in 0..(4-1) do
130.         sbuf <- sbuf +  "+-------"
131.     sbuf <- sbuf +  "+"
132.     println(sbuf)
134. // Begin here
135. let cmdArgs = System.Environment.GetCommandLineArgs()
136. if (Array.length cmdArgs > 1 && "-h" = cmdArgs.[1]) then
137.     printUsage 0
138.     exit(1)
140. makeTable 0

컴파일> fsc MakeRadixTable.fs

실행> MakeRadixTable

+-------+-------+-------+-------+
|  Dec  |   Bin |  Oct  |  Hex  |
+-------+-------+-------+-------+
|    0  |     0 |    0  |    0  |
|    1  |     1 |    1  |    1  |
|    2  |    10 |    2  |    2  |
|    3  |    11 |    3  |    3  |
|    4  |   100 |    4  |    4  |
|    5  |   101 |    5  |    5  |
|    6  |   110 |    6  |    6  |
|    7  |   111 |    7  |    7  |
|    8  |  1000 |   10  |    8  |
|    9  |  1001 |   11  |    9  |
|   10  |  1010 |   12  |    A  |
|   11  |  1011 |   13  |    B  |
|   12  |  1100 |   14  |    C  |
|   13  |  1101 |   15  |    D  |
|   14  |  1110 |   16  |    E  |
|   15  |  1111 |   17  |    F  |
+-------+-------+-------+-------+