Published at Sep 20 2018
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Instructions

Test suite

Solution

Write a function to convert from normal numbers to Roman Numerals.

The Romans were a clever bunch. They conquered most of Europe and ruled it for hundreds of years. They invented concrete and straight roads and even bikinis. One thing they never discovered though was the number zero. This made writing and dating extensive histories of their exploits slightly more challenging, but the system of numbers they came up with is still in use today. For example the BBC uses Roman numerals to date their programmes.

The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice these letters have lots of straight lines and are hence easy to hack into stone tablets).

```
1 => I
10 => X
7 => VII
```

There is no need to be able to convert numbers larger than about 3000. (The Romans themselves didn't tend to go any higher)

Wikipedia says: Modern Roman numerals ... are written by expressing each digit separately starting with the left most digit and skipping any digit with a value of zero.

To see this in practice, consider the example of 1990.

In Roman numerals 1990 is MCMXC:

1000=M 900=CM 90=XC

2008 is written as MMVIII:

2000=MM 8=VIII

See also: http://www.novaroma.org/via_romana/numbers.html

Go through the setup instructions for PL/SQL to get ready to code:

http://exercism.io/languages/plsql

Execute the tests by calling the `run`

method in the respective `ut_<exercise>#`

package.
The necessary code should be contained at the end of the test package.
As an example, the test for the *hamming* exercise would be run using

```
begin
ut_hamming#.run;
end;
/
```

The Roman Numeral Kata http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
create or replace package ut_numeral#
is
procedure run;
end ut_numeral#;
/
create or replace package body ut_numeral#
is
procedure test (
i_descn varchar2
,i_exp varchar2
,i_act varchar2
)
is
begin
if i_exp = i_act then
dbms_output.put_line('SUCCESS: ' || i_descn);
else
dbms_output.put_line('FAILURE: ' || i_descn || ' - expected ' || nvl('' || i_exp, 'null') || ', but received ' || nvl('' || i_act, 'null'));
end if;
end test;
procedure run
is
begin
test(i_descn => 'test_1', i_exp => 'I', i_act => numeral#.to_roman(1 ));
test(i_descn => 'test_2', i_exp => 'II', i_act => numeral#.to_roman(2 ));
test(i_descn => 'test_3', i_exp => 'III', i_act => numeral#.to_roman(3 ));
test(i_descn => 'test_4', i_exp => 'IV', i_act => numeral#.to_roman(4 ));
test(i_descn => 'test_5', i_exp => 'V', i_act => numeral#.to_roman(5 ));
test(i_descn => 'test_6', i_exp => 'VI', i_act => numeral#.to_roman(6 ));
test(i_descn => 'test_9', i_exp => 'IX', i_act => numeral#.to_roman(9 ));
test(i_descn => 'test_27', i_exp => 'XXVII', i_act => numeral#.to_roman(27 ));
test(i_descn => 'test_48', i_exp => 'XLVIII', i_act => numeral#.to_roman(48 ));
test(i_descn => 'test_59', i_exp => 'LIX', i_act => numeral#.to_roman(59 ));
test(i_descn => 'test_93', i_exp => 'XCIII', i_act => numeral#.to_roman(93 ));
test(i_descn => 'test_141', i_exp => 'CXLI', i_act => numeral#.to_roman(141 ));
test(i_descn => 'test_163', i_exp => 'CLXIII', i_act => numeral#.to_roman(163 ));
test(i_descn => 'test_402', i_exp => 'CDII', i_act => numeral#.to_roman(402 ));
test(i_descn => 'test_575', i_exp => 'DLXXV', i_act => numeral#.to_roman(575 ));
test(i_descn => 'test_911', i_exp => 'CMXI', i_act => numeral#.to_roman(911 ));
test(i_descn => 'test_1024', i_exp => 'MXXIV', i_act => numeral#.to_roman(1024));
test(i_descn => 'test_3000', i_exp => 'MMM', i_act => numeral#.to_roman(3000));
end run;
end ut_numeral#;
/
begin
ut_numeral#.run;
end;
/
```

```
create or replace function "ROMAN_NUMERALS"
(n in NUMBER)
return VARCHAR2
is
dnum number;
rnum varchar2(100) := null;
begin
dnum := n;
if dnum >= 1000
then
rnum := rpad('M',floor(dnum/1000),'M');
dnum := mod(dnum,1000);
end if;
if dnum >= 900
then
rnum := rnum || 'CM';
dnum := dnum - 900;
end if;
if dnum >= 500
then
rnum := rnum || 'D';
dnum := dnum - 500;
end if;
if dnum >= 400
then
rnum := rnum || 'CD';
dnum := dnum - 400;
end if;
if dnum >= 100
then
rnum := rnum || rpad('C',floor(dnum/100),'C');
dnum := mod(dnum,100);
end if;
if dnum >= 90
then
rnum := rnum || 'XC';
dnum := dnum - 90;
end if;
if dnum >= 50
then
rnum := rnum || 'L';
dnum := dnum - 50;
end if;
if dnum >= 40
then
rnum := rnum || 'XL';
dnum := dnum - 40;
end if;
if dnum >= 10
then
rnum := rnum || rpad('X',floor(dnum/10),'X');
dnum := mod(dnum,10);
end if;
if dnum >= 9
then
rnum := rnum || 'IX';
dnum := dnum - 9;
end if;
if dnum >= 5
then
rnum := rnum || 'V';
dnum := dnum - 5;
end if;
if dnum = 4
then
rnum := rnum || 'IV';
dnum := dnum - 4;
end if;
if dnum >= 1
then
rnum := rnum || rpad('I',dnum,'I');
end if;
return rnum;
end;
```

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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