Programming Fundamentals/Conditions/Lua

conditions.lua

-- This program asks the user to select Fahrenheit or Celsius conversion
-- and input a given temperature. Then the program converts the given 
-- temperature and displays the result.
--
-- References:
--     https://www.mathsisfun.com/temperature-conversion.html
--     https://www.lua.org/manual/5.1/manual.html

function get_choice()
    io.write("Enter F to convert to Fahrenheit or C to convert to Celsius:", "\n")
    choice = io.read()
    return choice
end

function get_temperature(label)
    local temperature
    
    print("Enter " .. label .. " temperature:")
    temperature = tonumber(io.read())
        
    return temperature
end

function calculate_celsius(fahrenheit)
    local celsius
    
    celsius = (fahrenheit - 32) * 5 / 9
        
    return celsius
end

function calculate_fahrenheit(celsius)
    local fahrenheit
    
    fahrenheit = celsius * 9 / 5 + 32
        
    return fahrenheit
end

function display_result(temperature, from_label, result, to_label)
    print(temperature .. "° " .. from_label .. " is " .. result .. "° " .. to_label)
end

function main()
    local choice
    local temperature
    local result
    
    choice = get_choice()
    if choice == "C" or choice == "c" then
        temperature = get_temperature("Fahrenheit")
        result = calculate_celsius(temperature)
        display_result(temperature, "Fahrenheit", result, "Celsius")
    elseif choice == "F" or choice == "f" then
        temperature = get_temperature("Celsius")
        result = calculate_fahrenheit(temperature)
        display_result(temperature, "Celsius", result, "Fahrenheit")
    else
        io.write("You must enter C to convert to Celsius or F to convert to Fahrenheit!", "\n")
    end
end

main()

Try It

Copy and paste the code above into one of the following free online development environments or use your own Lua compiler / interpreter / IDE.

• CodeChef
• Ideone
• repl.it
• TutorialsPoint

See Also

• Lua.org: Reference Manual

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