Number names
You are encouraged to solve this task according to the task description, using any language you may know.
ALGOL 68
PROC number words = (INT n)STRING:(
# returns a string representation of n in words. Currently
deals with anything from 0 to 999 999 999. #
[]STRING digits = []STRING
("zero","one","two","three","four","five","six","seven","eight","nine")[@0];
[]STRING teens = []STRING
("ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen")[@0];
[]STRING decades = []STRING
("twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety")[@2];
PROC three digits = (INT n)STRING: (
# does the conversion for n from 0 to 999. #
INT tens = n MOD 100 OVER 10;
INT units = n MOD 10;
(n >= 100|digits[n OVER 100] + " " + "hundred" + (n MOD 100 /= 0|" and "|"")|"") +
(tens /= 0|(tens = 1|teens[units]|decades[tens] + (units /= 0|"-"|""))) +
(units /= 0 AND tens /= 1 OR n = 0|digits[units]|"")
);
INT m = n OVER 1 000 000;
INT k = n MOD 1 000 000 OVER 1000;
INT u = n MOD 1000;
(m /= 0|three digits(m) + " million"|"") +
(m /= 0 AND (k /= 0 OR u >= 100)|", "|"") +
(k /= 0|three digits(k) + " thousand"|"") +
((m /= 0 OR k /= 0) AND u > 0 AND u < 100|" and " |: k /= 0 AND u /= 0|", "|"") +
(u /= 0 OR n = 0|three digits(u)|"")
);
on logical file end(stand in, (REF FILE f)BOOL: stop iteration);
on value error(stand in, (REF FILE f)BOOL: stop iteration);
DO # until user hits EOF #
INT n;
print("n? ");
read((n, new line));
print((number words(n), new line))
OD;
stop iteration:
SKIP
Example input with output:
n? 43112609 forty-three million, one hundred and twelve thousand, six hundred and nine