delphi 将整数转换为罗马数字

//数字转换罗马

function ToRoman(const iArabic: Integer): String;

const // S5 は 5 * 10^n を表すシンボル, S1 は 1 * 10^n を表すシンボル

ROMAN_SYMBOLS: array [-1.. 3] of record S5, S1: Char end = (

(S5: ' '; S1: ' '), // 範囲チェックを横着するためのダミー

(S5: ' '; S1: 'M'),

(S5: 'D'; S1: 'C'),

(S5: 'L'; S1: 'X'),

(S5: 'V'; S1: 'I')

);

begin

if (iArabic > 3999) or (iArabic < 1) then

Exit('');

var V := Int32(iArabic).ToString;

V := (StringOfChar('0', 4) + V).SubString(V.Length, 4); // 必ず4文字の文字列にする

var SB := TStringBuilder.Create;

try

for var i := 0 to 3 do //

begin

var C := ROMAN_SYMBOLS[i];

var P := ROMAN_SYMBOLS[i - 1]; //

var N := StrToIntDef(V.Chars[i], 0);

var F := N > 4;

var R := N mod 5;

if (R = 4) then // 剰余が 4 か？

begin

SB.Append(C.S1);

SB.Append(IfThen(F, P.S1, C.S5))

end

else

begin

if F then

SB.Append(C.S5);

SB.Append(C.S1, R);

end;

Result := SB.ToString;

finally

SB.DisposeOf;

end;

結果

12: XII

24: XXIV

42: XLII

49: XLIX

89: LXXXIX

299: CCXCIX

493: CDXCIII

1960: MCMLX

3999: MMMCMXCIX

//罗马转换数字

function ToAlabic(const iRomanNum: String): Integer;

const

ROMANS: array [-1.. 6] of record Number: Integer; Symbol: Char; end = (

(Number: 0; Symbol: ' '),

(Number: 1000; Symbol: 'M'),

(Number: 500; Symbol: 'D'),

(Number: 100; Symbol: 'C'),

(Number: 50; Symbol: 'L'),

(Number: 10; Symbol: 'X'),

(Number: 5; Symbol: 'V'),

(Number: 1; Symbol: 'I')

);

begin

Result := 0;

var i := 0;

var j := 0;

var Len := iRomanNum.Length;

while i < Len do

begin

var C := iRomanNum.Chars[i];

var N := iRomanNum.Chars[i + 1];

var CR := ROMANS[j];

var NR := ROMANS[j - 1];

if N = NR.Symbol then

begin

var D := 1;

while D < NR.Number do

D := D * 10;

Inc(Result, NR.Number - D div 10);

Inc(i, 2);

end

else

begin

if C = CR.Symbol then

begin

Inc(Result, CR.Number);

Inc(i);

end

else

Inc(j);

end

end;

結果

: 0

XII: 12

XXIV: 24

XLII: 42

XLIX: 49

LXXXIX: 89

CCXCIX: 299

CDXCIII: 493

MCMLX: 1960

MMMCMXCIX: 3999

program RomanNum;

{$APPTYPE CONSOLE}

{$R *.res}

uses

System.SysUtils,

uRomanNumHelper in 'uRomanNumHelper.pas'; //将上面2个函数放到这个单元里

const

NUMS: array[0.. 9] of Integer = (

0, 12, 24, 42, 49, 89, 299, 493, 1960, 3999

);

begin

//阿拉伯数字→罗马数字

Writeln('Alabic to Roman');

for var N in NUMS do

Writeln(N:4, ': ', ToRoman(N));

Writeln;

//罗马数字→阿拉伯数字

Writeln('Roman to Alabic');

for var N in NUMS do

begin

var R := ToRoman(N);

Writeln(R:9, ': ', ToAlabic(R):4);

end;

Readln;

end.

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