[Lua] Temperature Converter

Here is a simple temperature converter code written in Lua. It first ask for the user to enter in some value for the degrees in which will be converted. Then it ask the user to chose to convert Fahrenheit to Celsius or vise-versa. Then depending on which operation the user chose, it will convert the degrees and print out the new value.

Code:

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--Our functions to convert Fahrenheit to Celsius and vise-versa
function fahrenheit_to_celsius(fahrenheit)
        return (fahrenheit - 32) * 5 / 9
end

function celsius_to_fahrenheit(celsius)
        return celsius * 9 / 5 + 32
end

--Inifinite loop
while true do

        --The value to convert
        val = nil

        repeat

                io.write("Enter in a degrees value: ")
                temp = io.read()

                if tonumber(temp) then
                        val = tonumber(temp)
                else
                        io.write("That was an invalid number.\n")
                end


        until val ~= nil --Loop until the user enters in a valid number

        menu = nil

        repeat

                io.write("\nConvert Fahrenheit to Celsius: 1\n")
                io.write("Convert Celsius to Fahrenheit: 2\n")
                io.write("Chose option 1 or option 2: ")
                temp = io.read()

                if tonumber(temp) then
                        temp = tonumber(temp)

                        if temp == 1 or temp == 2 then
                                menu = tonumber(temp)
                        else
                                io.write(temp .. " is an invalid option.\n")
                        end
                else
                        io.write(temp .. " is an invalid number.\n\n")
                end


        until menu ~= nil --Loop until the user enters in a valid menu option

        --The converted degrees
        newVal = nil

        --Do the conversion
        if menu == 1 then
                newVal = fahrenheit_to_celsius(val)

                io.write("\n" .. val .. " degrees Fahrenheit is " .. newVal .. " degrees Celsius\n")
        else
                newVal = celsius_to_fahrenheit(val)

                io.write("\n" .. val .. " degrees Celsius is " .. newVal .. " degrees Fahrenheit\n")
        end

        io.write("Press the enter key to restart.")
        io.read()

        -- I operate in windows, if you use a version of Unix then replace cls with 'clear'
        os.execute("cls")


end

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