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FouadB's solution

to Roman Numerals in the PL/SQL Track

Published at Jul 13 2018 · 1 comment
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

Setup

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

http://exercism.io/languages/plsql

Running the Tests

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;
/

Source

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

Submitting Incomplete Solutions

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

ut_numeral#.plsql

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 package numeral#
is 
  function to_roman ( i_roman         pls_integer
  ) return varchar2;
  
end numeral#;
/

create or replace package body numeral#
is
  function to_roman ( i_roman         pls_integer
  )return varchar2
  is 
    roman_exception                   exception;
  begin
    if i_roman = 0 then
      raise roman_exception;
    else 
      return to_char(to_char(to_date(i_roman,'YYYY'), 'RRRR'), 'RN');
    end if;
    
  exception
    when roman_exception then    
      return ' The Romans never discovered though was the number ' || i_roman;  
      
  end to_roman;
end numeral#;
/

Community comments

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Avatar of hrodward

wow that's clever!

What can you learn from this solution?

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