Prime Number in Lua

Welcome to the Prime Number 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

--returns true if prime
function isPrime(n)
    comp = "Composite"
    prime = "Prime"
    usage = "Usage: please input a non-negative integer"
    local n = tonumber(n)
    --catch nil, negative and non int numbers
    if not n or n < 0 or (n % 1 ~= 0) then 
        print(usage)
    --catch 0 and 1
    elseif n < 2 then
        print(comp)
    --catch even number above 2
    elseif n > 2 and (n % 2 == 0) then 
        print(comp)
    --catch numbers that end in 5 or 0 (multiples of 5)
    elseif n>5 and (n % 5 ==0) then 
        print(comp)
    --now check for prime
    else
        --only do the odds
        result = prime
        for i = 3, math.sqrt(n), 2 do
            --did it divide evenly
            if (n % i == 0) then
                result = comp
            end
        end
        --can defeat optimus
        print(result)
    end
end

isPrime(arg[1])

Prime Number in Lua was written by:

• bhaskar_datta
• Jeremy Grifski

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 27 2019 23:51:57. As a result, documentation below may be outdated.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.