진법(radix) 표 만들기 예제 with OCaml

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 OCaml 소스 코드이다. 진법 변환에 필요한 함수

        int = atoi string radix           (즉, atoi :: string -> int -> int )
        string = itoa number radix    (즉, itoa :: int -> int -> string )

를 OCaml 코드로 자체 작성하여 사용하였다.

(아래의 소스는 Python 소스를 F# 소스로 일대일 변환 수정하고, 또 F# 소스를 OCaml 소스로 바꾼 것이라서 명령형 언어 특징을 위주로 작성되어 있다. 그래서 함수형 언어의 관점으로 보면 사이드 이팩트가 많아 난잡하게 보이는 소스이다.)

1. (*
2.  *  Filename: makeRadixTable.ml
3.  *            Show the radix table with 10-, 2-, 8-, 16-radices.
4.  *
5.  *  Execute: ocaml makeRadixTable.ml
6.  *
7.  *   Or
8.  *
9.  *  Compile: ocamlc -o makeRadixTable.exe makeRadixTable.ml
10.  *  Execute: makeRadixTable
11.  *
12.  *      Date:  2013. 1. 29.
13.  *    Author:  pkim __AT__scripts.pe.kr
14.  *)
16. exception RuntimeError of string
17. exception ValueError of string
19. open Printf ;;
21. let println s = printf "%s\n" s  ;;
23. let print s =  printf "%s" s  ;;
25. let printUsage dummy =
26.     println "Usage: makeRadixTable" ;
27.     println "Show the radix table with 10-, 2-, 8-, 16-radices."  ;;
29. let split_char sep str =
30.   let rec indices acc i =
31.     try
32.       let i = succ(String.index_from str i sep) in
33.       indices (i::acc) i
34.     with Not_found ->
35.       (String.length str + 1) :: acc
36.   in
37.   let is = indices [0] 0 in
38.   let rec aux acc = function
39.     | last::start::tl ->
40.         let w = String.sub str start (last-start-1) in
41.         aux (w::acc) (start::tl)
42.     | _ -> acc
43.   in
44.   aux [] is ;;
46. let sBASE36 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"  ;;
48. let rec sdup str n =
49.         match n with
50.         | 0 -> ""
51.         | k when k > 0 -> str ^ (sdup str (n - 1))
52.         | _ -> ""
54. let contains s1 s2 =
55.   try
56.     let len = String.length s2 in
57.     for i = 0 to (String.length s1) - len do
58.       if String.sub s1 i len = s2 then raise Exit
59.     done;
60.     false
61.   with Exit -> true ;;
63. let join list sep =
64.     let rec join' list acc =
65.         match list with
66.             | [] -> ""
67.             | [single] -> single
68.             | one::[two] ->
69.                         if acc = "" then one ^ sep ^ two
70.                                     else acc ^ one ^ sep ^ two
71.             | first::others -> join' others (acc ^ first ^ ", ")
72.                                         in
73.                                         join' list "" ;;
75. let str_reverse str =
        let len = String.length str in
76.     let res = String.create len in
77.     for i = 0 to pred len do
78.         let j = pred len - i in
79.         res.[i] <- str.[j]
80.     done;
81.     res ;;
83. let itoa num radix =
84.    let isNegative = ref false in
85.    let num1 = num + 0 in
86.    let numx = ref num1 in
88.    if num < 0 then begin
89.       isNegative := true ;
90.       numx := (-num)
91.    end ;
93.    let nnumx = !numx in
95.    let q1 = nnumx in
96.    let q = ref q1 in
97.    let r = ref 0 in
98.    let slen = ref 1 in
100.    while (!q >= radix) do
101.        r := !q mod radix ;
102.        q := !q / radix ;
103.        slen := !slen + 1
104.    done ;
106.    let sslen = !slen in
107.    let str = String.create sslen in
109.    let p1 = nnumx in
110.    let p = ref p1 in
112.    for i = 0 to sslen - 1 do
113.        r := !p mod radix ;
114.        p := !p / radix ;
115.        str.[i] <- sBASE36.[!r]
116.    done ;
118.    let str2 = str_reverse str in
119.    str2;;
121. let atoi s radix =
122.     let ret = ref 0 in
123.     let isNegative = ref false in
124.     let len = String.length s in
125.     let valx = ref 0 in
126.     let c1 = s.[0] in
127.     let c = ref c1 in
129.     if !c = '-' then 
130.        isNegative := true
131.     else if (!c >= '0' && !c <= '9') then
132.         ret := (int_of_char !c) - (int_of_char '0')
133.     else if (!c >= 'A' && !c <= 'Z') then
134.         ret := (int_of_char !c) - (int_of_char 'A') + 10
135.     else if (!c >= 'a' && !c <= 'z') then
136.         ret := (int_of_char !c) - (int_of_char 'a') + 10 ;
137.     if (!ret >= radix) then
138.         raise (ValueError (sprintf "Can not read \"%s\" (as radix %d): '%c' is invalid." s radix !c ) ) ;
140.     for i = 1 to len - 1 do
141.         c := s.[i] ;
142.         ret := (!ret)*radix  ;
143.         if (!c >= '0' && !c <= '9') then
144.             valx := int_of_char !c - int_of_char '0' 
145.         else if (!c >= 'A' && !c <= 'Z') then
146.             valx := int_of_char !c - int_of_char 'A' + 10
147.         else if (!c >= 'a' && !c <= 'z') then
148.             valx := int_of_char !c - int_of_char 'a' + 10 ;
149.         if (!valx >= radix) then 
                 raise (ValueError (sprintf "Can not read \"%s\" (as radix %d): '%c' is invalid." s radix !c ) ) ;
150.         ret := (!ret) + (!valx)
151.     done;
153.     if (!isNegative) then
154.         ret := (-(!ret) ) ;
156.     !ret ;;
159. let makeTable() =
160.     let sbuf = "" in
161.     let sbuf = sbuf ^ (sdup "+-------" 4) in
162.     let sbuf = sbuf ^ "+" in
163.     println sbuf ;
165.     let sbuf = "|  Dec" in
166.     let sbuf = sbuf ^  "\t|   Bin" in
167.     let sbuf = sbuf ^  "\t|  Oct" in
168.     let sbuf = sbuf ^  "\t|  Hex  |" in
169.     println sbuf ;
171.     let sbuf = ""  in
172.     let sbuf = sbuf ^ (sdup "+-------" 4) in
173.     let sbuf = sbuf ^  "+" in
174.     println sbuf ;
176.     for i = 0 to (16-1) do
177.         let sbuf = sprintf "|   %2d" i in
178.         let abuf = itoa i 2  in
179.         let tbuf = sprintf "\t|  %4s" abuf   in
180.         let sbuf = sbuf ^ tbuf   in
181.         let abuf = itoa i 8    in
182.         let tbuf = sprintf "\t|   %2s" abuf    in
183.         let sbuf = sbuf ^ tbuf    in
184.         let abuf = itoa i 16    in
185.         let tbuf = sprintf "\t|    %-2s |"  abuf    in
186.         let sbuf = sbuf ^  tbuf    in
187.         println sbuf
188.     done ;
190.     let sbuf = "" in
191.     let sbuf = sbuf ^ (sdup  "+-------" 4) in
192.     let sbuf = sbuf ^  "+" in
193.     println sbuf ;
194.     "" ;;
197. let main() =
198.     let cmdArgs = Sys.argv in
199.     if (Array.length cmdArgs > 1 && "-h" = cmdArgs.(1)) then begin
200.         printUsage() ;
201.         exit(1)
202.     end ;
203.     makeTable() ;;
205. main()

 

실행 결과:

+-------+-------+-------+-------+ | 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 | +-------+-------+-------+-------+