C++ Program to Make a Simple Calculator Using Switch Case

In this article, we'll show you how to write a C++ program to create a simple calculator that can add, subtract, multiply, or divide using a switch statement. The calculator works by taking two numbers(operands) and an operator (+, -, *, /) from the user, and then it performs the chosen operation.

Lets understand it better with an example:

Suppose the user enters: a = 5 and b = 4
Then, based on the chosen operator:

If the operator is +, the result is 5 + 4 = 9
If the operator is -, the result is 5 - 4 = 1
If the operator is *, the result is 5 * 4 = 20
If the operator is /, the result is 5 / 4 = 1.25

Using Switch Statement for Calculator Operations

We use a switch statement to perform calculator operations. A switch statement is a control structure in C++ that compares a variable against multiple values and runs the matching block of code. Here are the steps we follow:

• First, we ask the user to enter two numbers.
• Then, we ask which operation they want to perform.
• Based on the input symbol (+, -, *, /), we run the corresponding case using the switch statement.
• If the operator doesn't match any of the cases, we display an error message.

Example

Here's a complete C++ program to make a simple calculator that can add, subtract, multiply, or divide using the switch statement.

#include <iostream>
using namespace std;

int main() {
    double first, second; // To store user numbers
    char symbol; // To store the math operator

    // Ask for the operator
    cout << "Enter an operator (+, -, *, /): ";
    cin >> symbol;
    
    // Ask for the first number
    cout << "Enter the first number: ";
    cin >> first;

    // Ask for the second number
    cout << "Enter the second number: ";
    cin >> second;

    // Do the calculation based on the operator
    switch(symbol) {
        case '+':
            cout << "Result: " << first + second << endl;
            break;
        case '-':
            cout << "Result: " << first - second << endl;
            break;
        case '*':
            cout << "Result: " << first * second << endl;
            break;
        case '/':
            if (second != 0)
                cout << "Result: " << first / second << endl;
            else
                cout << "Error: Cannot divide by zero!" << endl;
            break;
        default:
            cout << "Error: Invalid operator!" << endl;
    }
    return 0;
}

The output below shows the result when the user selects '+' and enters 34 and 76, which gives an output of 110.

Enter an operator (+, -, *, /): +
Enter the first number: 34
Enter the second number: 76
Result: 110

Here, the user selects '/' and enters 98 and 4. The output is displayed below.

Enter an operator (+, -, *, /): /
Enter the first number: 98
Enter the second number: 4
Result: 24.5

Time Complexity: O(1) because the program performs a constant number of operations.

Space Complexity: O(1) because the program uses a constant amount of memory.