This page is about creating a simple calculator. A good way to do this is to first ask for what kind of operation to do, then ask the first variable, and then the second.

## Examples

### C++

```#include <iostream>
#include <cstdlib>

using namespace std;

int main()
{
double num1, num2;
int opselect;

cout << "\n welcome.";
cout << "this is a simple calculator.";
cout << "\n enter the first number: ";
cin >> num1;
cout << "enter operation: ";
cout << "\n  1 = addition";
cout << "\n  2 = subtraction";
cout << "\n  3 = multiplication";
cout << "\n  4 = division";
cout << "\n  - ";
cin >> opselect;
cout << "enter the second number: ";
cin >> num2;

cout << "CALCULATING";
cout << ".";
cout << ".";
cout << ".";

if (num1 == 2, num2 == 2, opselect == 1)
{
cout << num1 << " + " << num2 << " = " << "chair" << endl;
}
else
switch (opselect)
{
case 1:
cout << num1 << " + " << num2 << " = " << num1+num2 << endl;
break;
case 2:
cout << num1 << " - " << num2 << " = " << num1-num2 << endl;
break;
case 3:
cout << num1 << " X " << num2 << " = " << num1*num2 << end;
break;
case 4:
cout << num1 << " / " << num2 << " = " << num1/num2 << endl;
break;
}
system("PAUSE");
return 0;
}
```

From ProgrammingWiki, a Wikia wiki.

### Java

An open source calculator:

```import java.util.Scanner;
public class Main {
public static void main(String[] args) {
System.out.println("DOS-CALC::Created by AntoArts Entertainment");
System.out.println("----------------v1.0.00--------------------");
Scanner scan = new Scanner(System.in);
System.out.println("Type the name of the operation you want to use: ");
String operat = scan.next();
double a = scan.nextDouble();
System.out.println("Variable A is "+a+", please type in variable B: ");
double b = scan.nextDouble();
double z=a+b;
System.out.println(a+"+"+b+"="+z);
}
else if(operat.equals("subtraction")){
System.out.println("Counting with subtraction, please type in variable A: ");
double a = scan.nextDouble();
System.out.println("Variable A is "+a+", please type in variable B: ");
double b = scan.nextDouble();
double z=a-b;
System.out.println(a+"-"+b+"="+z);
}
else if(operat.equals("multiplication")){
System.out.println("Counting with multiplication, please type in variable A: ");
double a = scan.nextDouble();
System.out.println("Variable A is "+a+", please type in variable B: ");
double b = scan.nextDouble();
double z=a*b;
System.out.println(a+"*"+b+"="+z);
}
else if(operat.equals("division")){
System.out.println("Counting with division, please type in variable A: ");
double a = scan.nextDouble();
System.out.println("Variable A is "+a+", please type in variable B: ");
double b = scan.nextDouble();
double z=a/b;
System.out.println(a+"/"+b+"="+z);
}
else{
System.out.println("The operation you've requested wasn't avaiable");
System.out.println("Check spelling and make sure you typed the operation name lowercase");
}
}
}
```

## Lua

```-- Operators that the user will use.
local operators = {
["+"] = function(x, y) return x + y end,
["-"] = function(x, y) return x - y end,
["*"] = function(x, y) return x * y end,
["/"] = function(x, y) return x / y end
}

-- Error if the operator was not in the operator "list"
local function operatorError()
print "No such operator"
end

-- The input part of the calculator
print("Numbers:")
print("Enter first number:")