如何用 Pascal 寫 Roman Numerals

program assignment1c (input, output);
var number : integer;
charnum1 : integer;
charnum2 : integer;
charnum3 : integer;
charnum4 : integer;
outstr : string;

begin
outstr := ' ';

repeat
write('please input a number : ');
readln(number);
if (number < 1) or (number > 2500) then
writeln('number must be between 1 to 2500, please try again!');
until (number >= 1) and (number <= 2500);

charnum1 := number div 1000;
charnum2 := (number div 100) mod 10;
charnum3 := (number div 10) mod 10;
charnum4 := number mod 10;

case charnum1 of
1 : outstr := outstr + 'M';
2 : outstr := outstr + 'MM';
end;

case charnum2 of
1 : outstr := outstr + 'C';
2 : outstr := outstr + 'CC';
3 : outstr := outstr + 'CCC';
4 : outstr := outstr + 'CD';
5 : outstr := outstr + 'D';
6 : outstr := outstr + 'DC';
7 : outstr := outstr + 'DCC';
8 : outstr := outstr + 'DCCC';
9 : outstr := outstr + 'CM';
end;

case charnum3 of
1 : outstr := outstr + 'X';
2 : outstr := outstr + 'XX';
3 : outstr := outstr + 'XXX';
4 : outstr := outstr + 'XL';
5 : outstr := outstr + 'L';
6 : outstr := outstr + 'LX';
7 : outstr := outstr + 'LXX';
8 : outstr := outstr + 'LXXX';
9 : outstr := outstr + 'XC';
end;

case charnum4 of
1 : outstr := outstr + 'I';
2 : outstr := outstr + 'II';
3 : outstr := outstr + 'III';
4 : outstr := outstr + 'IV';
5 : outstr := outstr + 'V';
6 : outstr := outstr + 'VI';
7 : outstr := outstr + 'VII';
8 : outstr := outstr + 'VIII';
9 : outstr := outstr + 'IX';
end;

writeln('The roman numeral of ', number, ' is : ', outstr)

end.