Module:NumberSpell

-- This module converts a number into its written English form. -- For example, "2" becomes "two", and "79" becomes "seventy-nine".

local getArgs = require('Dev:Arguments').getArgs

local p = {}

local max = 100 -- The maximum number that can be parsed.

local ones = { [0] = 'zero', [1] = 'one', [2] = 'two', [3] = 'three', [4] = 'four', [5] = 'five', [6] = 'six', [7] = 'seven', [8] = 'eight', [9] = 'nine' }

local specials = { [10] = 'ten', [11] = 'eleven', [12] = 'twelve', [13] = 'thirteen', [15] = 'fifteen', [18] = 'eighteen', [20] = 'twenty', [30] = 'thirty', [40] = 'forty', [50] = 'fifty', [60] = 'sixty', [70] = 'seventy', [80] = 'eighty', [90] = 'ninety', [100] = 'one hundred' }

local formatRules = { {num = 90, rule = 'ninety-%s'}, {num = 80, rule = 'eighty-%s'}, {num = 70, rule = 'seventy-%s'}, {num = 60, rule = 'sixty-%s'}, {num = 50, rule = 'fifty-%s'}, {num = 40, rule = 'forty-%s'}, {num = 30, rule = 'thirty-%s'}, {num = 20, rule = 'twenty-%s'}, {num = 10, rule = '%steen'} }

function p.main(frame) local args = getArgs(frame) local num = tonumber(args[1]) local success, result = pcall(p._main, num) if success then return result else return string.format(' Error: %s ', result) -- "result" is the error message. end return p._main(num) end

function p._main(num) if type(num) ~= 'number' or math.floor(num) ~= num or num max then error('input must be an integer between 0 and ' .. tostring(max), 2) end -- Check for numbers from 0 to 9. local onesVal = ones[num] if onesVal then return onesVal end -- Check for special numbers. local specialVal = specials[num] if specialVal then return specialVal end -- Construct the number from its format rule. onesVal = ones[num % 10] if not onesVal then error('Unexpected error parsing input ' .. tostring(num)) end for i, t in ipairs(formatRules) do		if num >= t.num then return string.format(t.rule, onesVal) end end error('No format rule found for input ' .. tostring(num)) end

return p