Simple Calculator Program in C++

Introduction

In this lab, we will be creating a simple calculator program using C++. This program will use switch statements to perform basic arithmetic operations such as addition, subtraction, multiplication and division.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL cpp(("C++")) -.-> cpp/BasicsGroup(["Basics"]) cpp(("C++")) -.-> cpp/ControlFlowGroup(["Control Flow"]) cpp(("C++")) -.-> cpp/IOandFileHandlingGroup(["I/O and File Handling"]) cpp(("C++")) -.-> cpp/SyntaxandStyleGroup(["Syntax and Style"]) cpp/BasicsGroup -.-> cpp/variables("Variables") cpp/ControlFlowGroup -.-> cpp/switch("Switch") cpp/IOandFileHandlingGroup -.-> cpp/output("Output") cpp/IOandFileHandlingGroup -.-> cpp/user_input("User Input") cpp/IOandFileHandlingGroup -.-> cpp/files("Files") cpp/SyntaxandStyleGroup -.-> cpp/comments("Comments") cpp/SyntaxandStyleGroup -.-> cpp/code_formatting("Code Formatting") subgraph Lab Skills cpp/variables -.-> lab-96238{{"Program for Simple Calculator"}} cpp/switch -.-> lab-96238{{"Program for Simple Calculator"}} cpp/output -.-> lab-96238{{"Program for Simple Calculator"}} cpp/user_input -.-> lab-96238{{"Program for Simple Calculator"}} cpp/files -.-> lab-96238{{"Program for Simple Calculator"}} cpp/comments -.-> lab-96238{{"Program for Simple Calculator"}} cpp/code_formatting -.-> lab-96238{{"Program for Simple Calculator"}} end

Set up the program file

First, we need to create the main.cpp file in the ~/project directory. Use your favorite text editor to create a new file named main.cpp.

touch ~/project/main.cpp

Include necessary libraries

In the main.cpp file, we need to include the iostream header file.

#include <iostream>

Add the main function

Next, we need to add the main function to our program.

int main() {
    // Code goes here
    return 0;
}

Declare variables and ask for user input

In the main function, we need to declare the necessary variables and ask the user for input.

int main() {
    char op;
    float num1, num2;

    std::cout << "Enter operator either + or - or * or /: ";
    std::cin >> op;

    std::cout << "\nEnter two operands: ";
    std::cin >> num1 >> num2;

    // Code goes here

    return 0;
}

Add switch statement

We can use a switch statement to perform the necessary operation based on the operator entered by the user.

int main() {
    char op;
    float num1, num2;

    std::cout << "Enter operator either + or - or * or /: ";
    std::cin >> op;

    std::cout << "\nEnter two operands: ";
    std::cin >> num1 >> num2;

    switch(op) {
        case '+':
            std::cout << "\nResult is: " << num1 + num2;
            break;

        case '-':
            std::cout << "\nResult is: " << num1 - num2;
            break;

        case '*':
            std::cout << "\nResult is: " << num1 * num2;
            break;

        case '/':
            std::cout << "\nResult is: " << num1 / num2;
            break;

        default:
            // If the operator is other than +, -, * or /, error message is shown
            std::cout << "Error! operator is not correct";
            break;
    }

    return 0;
}

Compile and run the program

Compile the program using the following command in the terminal of Ubuntu system:

g++ ~/project/main.cpp -o main && ./main

Summary

In this lab, we created a simple calculator program using C++. We used switch statements to perform basic arithmetic operations based on user input. By following the steps outlined in this lab, you should now have a working knowledge of how to create a basic calculator program in C++.