Making a Calculator from Scratch

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#1

Hello.

I want to make a calculator on roblox just for fun and I am writing this to see what would be the most efficient way on doing it with the UI that I have already created!

How should I structure the script?

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#2

Well, you’d need to detect when the button is pressed and I’d store it in an int value or in the script.
Then with the first number you need to get an operator; when an operator is chosen hide the initial value the user typed out and ready it for another number to be typed in

#3

whipping up a test script right now.

#4 
--Make Variables (Store These In The Script Through Number Value When You Start Modifying This And Then Reference Their Values Here)--
local NumberSetOne = 0
local NumberSetTwo = 0
local MathType = "None"

--Have A Function That Adds Numbers Together (Not Addition Just Adding To String)--
local function NumPressed(Num)
	if MathType == "None" then
		if NumberSetOne ~= 0 then
			NumberSetOne = NumberSetOne..Num
		else
			NumberSetOne = Num
		end
	else
		if NumberSetTwo ~= 0 then
			NumberSetTwo = NumberSetTwo..Num
		else
			NumberSetTwo = Num
		end
	end
end

--Clears The Numbers--
local function Clear()
	NumberSetOne = 0
	NumberSetTwo = 0
    MathType = "None"
end

--Function For When The Player Pressed "*" or "+" or "/" etc.--
local function SetMathType(T)
	MathType = T
end

--Function For When The Player Hits "="--
local function PerformCalc()
	if MathType == "Multiplication" then
		NumberSetOne = NumberSetOne * NumberSetTwo
		print(NumberSetOne)
	elseif MathType == "Addition" then
		NumberSetOne = NumberSetOne + NumberSetTwo
		print(NumberSetOne)
	elseif MathType == "Division" then
		NumberSetOne = NumberSetOne / NumberSetTwo
		print(NumberSetOne)
	elseif MathType == "Subtraction" then
		NumberSetOne = NumberSetOne - NumberSetTwo
		print(NumberSetOne)
	else
		print("No MathType Set")
	end
	MathType = "None"
end

--Activating The Functions--
ClearGUIButton.Activated:Connect(Clear())

EqualsGUIButton.Activated:Connect(PerformCalc())

--Make As Many Of These As there Are Number Buttons
NumberButton1.Activated:Connect(NumPressed(1))

--Make As Many Of These As there Are Math Type Buttons
AdditionButton.Activated:Connect(NumPressed("Addition"))

Then you can use when the number values in the script change you can change the display through another script.

Also this script is untested so i cant tell you how well this works this was mostly a proof of concept and needs to be modified to be used.

#5

Hello! Since I’ve seen this post (around 1-2 hours ago) I have started making a calculator from scratch to see if I can actually make one, I have color picked every color from the picture so the UI shouldn’t look bad. The model only contains one local script that you can check for anything you want, it’s not virused lol. Here it is: Calculator GUI - Roblox I hope I helped!

#6

Also, if you would like to adapt a script to your already existing UI, that’s fine but you will have to change some variables and the names of the buttons and things. Here’s the source code anyways:

--Script Made by Sarpomijon11 14/10/2022

local MainFrame = script.Parent:WaitForChild("MainFrame")
local ButtonsHolder = MainFrame:WaitForChild("ButtonsHolder")
local ResultText = MainFrame:WaitForChild("Result")
local Symbol = MainFrame:WaitForChild("Symbol")

local FirstNumber = 0
local SecondNumber = 0
local SwitchToSecondNumber = false
local SymbolSelected

local MathFunctions = {
	["/"] = function(a,b) return a/b end;
	["*"] = function(a,b) return a*b end;
	["-"] = function(a,b) return a-b end;
	["+"] = function(a,b) return a+b end;
	["%"] = function(a,b) return a/100*b end;
}

local Symbols = {
	["="] = function()
		if not (FirstNumber and SecondNumber) then return end
		FirstNumber = tonumber(FirstNumber) ; SecondNumber = tonumber(SecondNumber)
		local NumberResult = MathFunctions[SymbolSelected](FirstNumber,SecondNumber)
		ResultText.Text = AddCommas(NumberResult)
		FirstNumber = NumberResult
		SecondNumber = 0
		Symbol.Text = ""
	end,
	["AC"] = function()
		FirstNumber = 0
		SecondNumber = 0
		ResultText.Text = "0"
		Symbol.Text = ""
	end,
}

function AddCommas(Number)
	Number = tostring(Number)
	local Split = string.split(Number,"")
	if #Split > 3 then
		for i = #Split,1,-3 do
			Split[i] = i ~= #Split and Split[i].."," or Split[i]
		end
	end
	Number = ""
	for i = 1,#Split,1 do Number = Number..Split[i] end
	return Number
end

for i,Button in pairs(ButtonsHolder:GetChildren()) do
	if Button:IsA("TextButton") then
		Button.MouseButton1Down:Connect(function()
			if tonumber(Button.Text) or Button.Text == "." then
				if SwitchToSecondNumber then
					SecondNumber = (SecondNumber == 0 and Button.Text ~=".") and Button.Text or tostring(SecondNumber)..Button.Text
					ResultText.Text = AddCommas(SecondNumber)
				else
					FirstNumber = (FirstNumber == 0 and Button.Text ~=".") and Button.Text or tostring(FirstNumber)..Button.Text
					ResultText.Text = AddCommas(FirstNumber)
				end
			elseif MathFunctions[Button.Text] then
				Symbol.Text = Button.Text
				SwitchToSecondNumber = true
				SymbolSelected = Button.Text
			elseif Symbols[string.upper(Button.Text)] then Symbols[string.upper(Button.Text)]() end
		end)
	end
end
#7

Ended up using my own script after messing with it for a bit! I used a little bit of everyone’s idea’s and ended up with this, if anyone needs to use it!

--// Items
--# Objects
local Calculator = script.Parent

local One, Two, Three, Four, Five, Six, Seven, Eight, Nine, Zero = Calculator:FindFirstChild('One'), Calculator:FindFirstChild('Two'), Calculator:FindFirstChild('Three'), Calculator:FindFirstChild('Four'), Calculator:FindFirstChild('Five'), Calculator:FindFirstChild('Six'), Calculator:FindFirstChild('Seven'), Calculator:FindFirstChild('Eight'), Calculator:FindFirstChild('Nine'), Calculator:FindFirstChild('Zero')
local Equal, Add, Subtract, Multiply, Divide = Calculator:FindFirstChild('Equal'), Calculator:FindFirstChild('Add'), Calculator:FindFirstChild('Subtract'), Calculator:FindFirstChild('Multiply'), Calculator:FindFirstChild('Divide')
local Clear, System = Calculator:FindFirstChild('Clear'), Calculator:FindFirstChild('System')

local Output = Calculator:FindFirstChild('Output')

--# Variables
local valueOne = 0
local valueTwo = 0
local Operation = nil

local Solution = nil

--// Scripts
--# numberClicked
local function numberClicked(numberClicked)
	
	if Solution then
		
		valueOne, valueTwo = 0, 0
		Operation, Solution = nil, nil
		
	end
	
	if Operation == nil then
		
		if valueOne == 0 then

			valueOne = numberClicked

		elseif valueOne == '-0' then

			valueOne = '-'..numberClicked

		else

			valueOne = valueOne..numberClicked

		end
		
	else
		
		if valueTwo == 0 then

			valueTwo = numberClicked

		elseif valueTwo == '-0' then
			
			valueTwo = '-'..numberClicked
			
		else

			valueTwo = valueTwo..numberClicked

		end
		
	end
	
end

One.Activated:Connect(function() numberClicked(1) end)
Two.Activated:Connect(function() numberClicked(2) end)
Three.Activated:Connect(function() numberClicked(3) end)
Four.Activated:Connect(function() numberClicked(4) end)
Five.Activated:Connect(function() numberClicked(5) end)
Six.Activated:Connect(function() numberClicked(6) end)
Seven.Activated:Connect(function() numberClicked(7) end)
Eight.Activated:Connect(function() numberClicked(8) end)
Nine.Activated:Connect(function() numberClicked(9) end)
Zero.Activated:Connect(function() numberClicked(0) end)

--# operationClicked
local function operationClicked(operationClicked)
	
	if operationClicked == '+' then
		
		Operation = '+'
		
	elseif operationClicked == '-' then
		
		Operation = '-'
		
	elseif operationClicked == '*' then
		
		Operation = '*'
		
	elseif operationClicked == '/' then
		
		Operation = '/'
		
	elseif operationClicked == '=' then
		
		if (valueOne ~= 0) and (valueTwo ~= 0) then
			
			valueOne = tonumber(valueOne)
			valueTwo = tonumber(valueTwo)
			
			if Operation == '+' then

				Solution = (valueOne + valueTwo)

			elseif Operation == '-' then

				Solution = (valueOne - valueTwo)

			elseif Operation == '*' then

				Solution = (valueOne * valueTwo)

			elseif Operation == '/' then

				Solution = (valueOne / valueTwo)
				
			end
			
		end
		
	end
	
end

Add.Activated:Connect(function() operationClicked('+') end)
Subtract.Activated:Connect(function() operationClicked('-') end)
Multiply.Activated:Connect(function() operationClicked('*') end)
Divide.Activated:Connect(function() operationClicked('/') end)
Equal.Activated:Connect(function() operationClicked('=') end)

--# buttonClicked
local function buttonClicked(buttonClicked)
	
	if buttonClicked == 'clear' then
		
		valueOne, valueTwo = 0, 0
		Operation, Solution = nil, nil
		
	elseif buttonClicked == 'sys' then
		
		if (Solution) then return end
		
		if Operation then
			
			valueTwo = '-'..valueTwo
			
		else
			
			valueOne = '-'..valueOne
			
		end
		
	end
	
end

Clear.Activated:Connect(function() buttonClicked('clear') end)
System.Activated:Connect(function() buttonClicked('sys') end)

--# Show Text
while true do
	
	if (not valueOne) and (not valueTwo) then
		
		Output.Text = '0'
		
	elseif (valueOne) and (not Operation) then
		
		Output.Text = valueOne
		
	elseif (valueTwo) and (not Solution) then
		
		Output.Text = valueTwo
		
	elseif (Solution) then
		
		Output.Text = Solution
		
	end

	wait()
	
end
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#8

is there a way to use more than two values but still have a limit?

#9

I haven’t worked on the project for a while but, here is the final script I ended up with:

--// Items
--# Objects
local Calculator = script.Parent

local One, Two, Three, Four, Five, Six, Seven, Eight, Nine, Zero = Calculator:FindFirstChild('One'), Calculator:FindFirstChild('Two'), Calculator:FindFirstChild('Three'), Calculator:FindFirstChild('Four'), Calculator:FindFirstChild('Five'), Calculator:FindFirstChild('Six'), Calculator:FindFirstChild('Seven'), Calculator:FindFirstChild('Eight'), Calculator:FindFirstChild('Nine'), Calculator:FindFirstChild('Zero')
local Equal, Add, Subtract, Multiply, Divide = Calculator:FindFirstChild('Equal'), Calculator:FindFirstChild('Add'), Calculator:FindFirstChild('Subtract'), Calculator:FindFirstChild('Multiply'), Calculator:FindFirstChild('Divide')
local Clear, System = Calculator:FindFirstChild('Clear'), Calculator:FindFirstChild('System')

local Output = Calculator:FindFirstChild('Output')

--# Variables
local valueOne = 0
local valueTwo = 0
local Operation = nil

local Solution = nil

--// Scripts
--# numberClicked
local function numberClicked(numberClicked)
	
	if Operation == nil then
		
		if valueOne == 0 then

			valueOne = numberClicked

		elseif valueOne == '-0' then

			valueOne = '-'..numberClicked

		else

			valueOne = valueOne..numberClicked

		end
		
	else
		
		if valueTwo == 0 then

			valueTwo = numberClicked

		elseif valueTwo == '-0' then
			
			valueTwo = '-'..numberClicked
			
		else

			valueTwo = valueTwo..numberClicked

		end
		
	end
	
end

One.Activated:Connect(function() numberClicked(1) end)
Two.Activated:Connect(function() numberClicked(2) end)
Three.Activated:Connect(function() numberClicked(3) end)
Four.Activated:Connect(function() numberClicked(4) end)
Five.Activated:Connect(function() numberClicked(5) end)
Six.Activated:Connect(function() numberClicked(6) end)
Seven.Activated:Connect(function() numberClicked(7) end)
Eight.Activated:Connect(function() numberClicked(8) end)
Nine.Activated:Connect(function() numberClicked(9) end)
Zero.Activated:Connect(function() numberClicked(0) end)

--# operationClicked
local function operationClicked(operationClicked)
	
	if (Solution) then
		valueOne, valueTwo = Solution, 0
		Solution = nil
	end
	
	if operationClicked == '+' then

		Operation = '+'

	elseif operationClicked == '-' then

		Operation = '-'

	elseif operationClicked == '*' then

		Operation = '*'

	elseif operationClicked == '/' then

		Operation = '/'

	elseif operationClicked == '=' then

		if (valueOne ~= 0) and (valueTwo ~= 0) then

			valueOne = tonumber(valueOne)
			valueTwo = tonumber(valueTwo)

			if Operation == '+' then

				Solution = (valueOne + valueTwo)

			elseif Operation == '-' then

				Solution = (valueOne - valueTwo)

			elseif Operation == '*' then

				Solution = (valueOne * valueTwo)

			elseif Operation == '/' then

				Solution = (valueOne / valueTwo)

			end

		end

	end
	
end

Add.Activated:Connect(function() operationClicked('+') end)
Subtract.Activated:Connect(function() operationClicked('-') end)
Multiply.Activated:Connect(function() operationClicked('*') end)
Divide.Activated:Connect(function() operationClicked('/') end)
Equal.Activated:Connect(function() operationClicked('=') end)

--# buttonClicked
local function buttonClicked(buttonClicked)
	
	if buttonClicked == 'clear' then
		
		valueOne, valueTwo = 0, 0
		Operation, Solution = nil, nil
		
	elseif buttonClicked == 'sys' then
		
		if (Solution) then return end
		
		if Operation then
			
			valueTwo = '-'..valueTwo
			
		else
			
			valueOne = '-'..valueOne
			
		end
		
	end
	
end

Clear.Activated:Connect(function() buttonClicked('clear') end)
System.Activated:Connect(function() buttonClicked('sys') end)

--# Show Text
while true do
	
	if (not valueOne) and (not valueTwo) then
		
		Output.Text = '0'
		
	elseif (valueOne) and (not Operation) then
		
		Output.Text = valueOne
		
	elseif (valueTwo) and (not Solution) then
		
		Output.Text = valueTwo
		
	elseif (Solution) then
		
		Output.Text = Solution
		
	end

	wait()
	
end
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