Factorial in Lua

Welcome to the Factorial in Lua page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

--
-- Calculate the factorial
--
factorial = function(num)
    product = 1
    if num > 1
    then
        for i = 2, num 
        do
            product = product * i
        end
    end
    return product
end

--
-- Main executable logic
--
main = function(input)
    maxInput = 20
    usage = "Usage: please input a non-negative integer"

    if not (input == nil or input == "")
    then
        inputValidation = input:gsub('[0-9]','')
        if inputValidation:len() == 0
        then
            inputNum = tonumber(input)
            if inputNum > maxInput
            then
                print('Input of ' .. inputNum .. ' is too large to calculate a factorial for. Max input is ' .. maxInput .. '.')
            else
                print(factorial(tonumber(input)))
            end
        else
            print(usage)
        end
    else
        print(usage)
    end

end

-- Run the script
main(arg[1])

Factorial in Lua was written by:

• Jeremy Grifski
• Matt Wiley

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 15 2020 19:22:39. The solution was first committed on Oct 10 2019 12:43:45. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.