Calculator Program in C++

Calculator Program in C++

A calculator program is a simple instructional and case action program that does numerical calculations. We can carry out simple to complex operations depending on the type of our requirement. There are hundreds of ways to make a calculator in C++ ranging from simple to complex instructions.

Let us look at some of the main ways to make a calculator in C++

Example 1:

 #include<bits/stdc++.h>
 using namespace std;
 int main()
 {
     char operation;
     float number1, number2;
     cout<<"Enter the operation you want to perform: ";
     cin >> operation;
     cout<<"Enter two numbers: ";
     cin >> number1 >> number2;
 switch (operation) {
         case '+':
             cout << number1 + number2;
             break;
         case '-':
             cout << number1 - number2;
             break;
         case '*':
             cout << number1 * number2;
             break;
         case '/':
             cout << number1 / number2;
             break;
         default:
             cout << "Invalid Input";
             break;
     } 
     return 0; 
 }  

Output:

Explanation:

First, we have defined a variable name operation and seek the user to enter what kind of operation he/she wants to perform. The next task is taking two numbers, which is defined in the code as number1 and number2 respectively. The next task is to define switch cases.

A switch case shifts the operation based on the entry by the user and performs the necessary action. The control flow of the switch case can be easily understood from the code itself, though below algorithmic logic and flowchart explains it leaving no doubts.

Algorithm:

START

1. Print "Enter the operation you want to perform"

• Enter your choice

• Enter two operands

• If the user enters + or - or * or / then follow the instructions or     else return default i.e invalid option.

• Switch(operator)

    A.  case +:

                   i.                 Print ‘Addition’.

                    ii.                Print result of addition.

                   iii.               break

B.        case -:

                   i.                 Print ‘Subtraction’.

                   ii.                Print result of subtraction.

            break

C.        case *:

                   i.                 Print ‘Multiplication’.

                   ii.                Print result of multiplication.

                   iii.               break

    D.  case /:

                   i.                 Print ‘Division’.

                   ii.                Print result of division.

                   iii.               break

          E.      default:

                   i.        Print ‘Invalid Option’.

STOP

Let us look at another example to perform all the operations together so that users don’t have to seek each and every-time for it.

Example 2:

 #include<bits/stdc++.h>
 using namespace std;
 template <class T>
 class Calculator
 {
 private:
         T num1, num2;
 public:
         Calculator(T n1, T n2)
         {
                 num1 = n1;
                 num2 = n2;
         }
         void displayResult()
         {
                 cout << "Numbers are: " << num1 << " and " << num2 << "." << endl;
                 cout << "Addition is: " << add() << endl;
                 cout << "Subtraction is: " << subtract() << endl;
                 cout << "Product is: " << multiply() << endl;
                 cout << "Division is: " << divide() << endl;
         }
         T add() { return num1 + num2; }
         T subtract() { return num1 - num2; }
         T multiply() { return num1 * num2; }
         T divide() { return num1 / num2; }
 };
 int main()
 {
         Calculator<int> intCalc(2, 1);
         Calculator<float> floatCalc(2.4, 1.2);
         cout << "Int results:" << endl;
         intCalc.displayResult();
         cout << endl << "Float results:" << endl;
         floatCalc.displayResult();
         return 0;
 } 

Output:

Note: The above code is for integer and float data-types.

Explanation:

In the above code, the Object-Oriented Programming methodology is used just to showcase the standard procedure of a calculator. It is quite applicable to using the Standard Template Library(STL) in C++. The class Calculator is defined using the template class T to reduce the complexity of writing repeating terms more often. Using template class increases the accessibility of the program. Therefore, intCalc() and floatCalc() are the two functions defined to calculate values for integers and float as well. Another function displayResult() displays the result on the screen after the code execution.

Template class syntax can be understood by the following pseudo code:

 template <class type> return_type func_name(parameter list)
 {
 // body of function
 } 

Also, the add(), subtract(), divide(), multiply() are the functions which have both integer and float return type. These functions have two arguments num1 and num2 which are already initialized in the driver code as (2,1) for intCalc() function and (2.4, 1.2) for floatCalc() function.

The above code returns 0 as exit code since it is normal termination.

Summary

There are various ways to code a simple calculator program in C++. The Standard Template Library (STL) provides in-built features to ease the process of writing code for certain types of requirements. The above approaches range from simple to complex programming paradigms depending on how to fetch the operation. Also, C++ provides various other methods that can be used to normalize or complicate the output. The above codes can also be changed to make various other calculators like a Scientific Calculator which has infinite usage in the higher mathematical calculations.