Number names: Difference between revisions

</pre>

=={{header|Prolog}}==

<lang prolog>

:- module(spell, [spell/2]).

%

% spell numbers up to the nonillions.

%

ones(1, "one"). ones(2, "two"). ones(3, "three"). ones(4, "four"). ones( 5, "five").

ones(6, "six"). ones(7, "seven"). ones(8, "eight"). ones(9, "nine"). ones(10, "ten").

ones(11, "eleven"). ones(12, "twelve"). ones(13, "thirteen").

ones(14, "fourteen"). ones(15, "fifteen"). ones(16, "sixteen").

ones(17, "seventeen"). ones(18, "eighteen"). ones(19, "nineteen").

tens(2, "twenty"). tens(3, "thirty"). tens(4, "forty"). tens(5, "fifty").

tens(6, "sixty"). tens(7, "seventy"). tens(8, "eighty"). tens(9, "ninety").

group( 1, 'thousand'). group( 2, "million"). group(3, "bilion").

group( 4, "trillion"). group( 5, "quadrillion"). group(6, "quintillion").

group( 7, "sextilion"). group( 8, "septillion"). group(9, "octillion").

group(10, "nonillion"). group(11, "decillion").

spellgroup(N, G) :- G is floor(log10(N) / 3).

spell(N, S) :-

N < 0, !,

NegN is -N, spell(NegN, S0),

string_concat("negative ", S0, S).

spell(0, "zero") :- !.

spell(N, S) :- between(1, 19, N), ones(N, S), !.

spell(N, S) :-

N < 100, !,

divmod(N, 10, Tens, Ones),

tens(Tens, StrTens), ones_part(Ones, StrOnes),

string_concat(StrTens, StrOnes, S).

spell(N, S) :-

N < 1000, !,

divmod(N, 100, Hundreds, Tens),

ones(Hundreds, H), string_concat(H, " hundred", StrHundreds),

tens_part(Tens, StrTens),

string_concat(StrHundreds, StrTens, S).

spell(N, S) :-

spellgroup(N, G), group(G, StrG),

M is 10**(3*G), divmod(N, M, Group, Rest),

spell(Group, S1),

spell_remaining(Rest, S2),

format(string(S), "~w ~w~w", [S1, StrG, S2]).

ones_part(0, "") :- !.

ones_part(N, S) :-

ones(N, StrN),

string_concat("-", StrN, S).

tens_part(0, "") :- !.

tens_part(N, S) :-

spell(N, Tens),

string_concat(" and ", Tens, S).

spell_remaining(0, "") :- !.

spell_remaining(N, S) :-

spell(N, Rest),

string_concat(", ", Rest, S).

</lang>

{{Out}}

<pre>

?- use_module(library(spell)).

true.

?- spell(0, Txt).

Txt = "zero".

?- spell(73, Txt).

Txt = "seventy-three".

?- spell(-144001, Txt).

Txt = "negative one hundred and forty-four thousand, one".

?- BigPrime is 2**89 - 1, spell(BigPrime, Txt).

BigPrime = 618970019642690137449562111,

Txt = "six hundred and eighteen septillion, nine hundred and seventy sextilion, nineteen quintillion, six hundred and forty-two quadrillion, six hundred and ninety trillion, one hundred and thirty-seven bilion, four hundred and forty-nine million, five hundred and sixty-two thousand, one hundred and eleven".