Question

Write C++ statements to do the following: a. Declare int variable num1 and num2. b. Prompt the user to input two numbers. c. Input the first number in num1 and the second number in num2. d. Output num1, num2, and 2 times num1 minus num2. Your output must identify each number and the expression.

Short answer

Use C++ code to declare variables, prompt and input numbers, and output the results with explanations.

Step-by-step solution

Declare Variables

Start by declaring the integer variables. In C++, you can declare the variables using the `int` keyword. Here is the statement to declare `num1` and `num2`: ```cpp int num1, num2; ```

Prompt for User Input

Next, prompt the user to enter two numbers. You can use the `cout` statement to display the message on the screen. Here is how you do it: ```cpp std::cout << "Enter two numbers: "; ```

Input the Numbers

Read the input numbers provided by the user into `num1` and `num2`. Use the `cin` statement to read the input and store it in the variables: ```cpp std::cin >> num1 >> num2; ```

Output the Results

Finally, output `num1`, `num2`, and the result of the expression `2 * num1 - num2`. Use descriptive text to identify what each output represents: ```cpp std::cout << "num1 = " << num1 << std::endl; std::cout << "num2 = " << num2 << std::endl; std::cout << "2 times num1 minus num2 = " << (2 * num1 - num2) << std::endl; ```

Key concepts

Variables in C++

Variables are essential in any programming language, allowing you to store data that your programs can manipulate. In C++, we declare variables by specifying the type before the variable name. For example, the statement `int num1, num2;` declares two integer variables, `num1` and `num2`. The keyword `int` stands for integer, which means that these variables can hold whole numbers.
Choosing the right variable type ensures that your program effectively manages memory and data types. Always initialize variables whenever possible to avoid undefined behavior in your programs.

User Input in C++

Taking input from the user is a common task in C++ programming. It enables programs to interact with the individual using the software. To prompt the user for input, we use the `cout` object from the `` library.
For instance, when we write `std::cout << "Enter two numbers: ";`, it displays the prompt message to the screen, guiding the user to input data. After prompting, the `cin` object is used to receive input. This is akin to asking the user a question and then waiting to hear their response.

• `std::cin >> num1 >> num2;` reads the two numbers entered by the user and stores them in `num1` and `num2` respectively.

Ensure you guide the user clearly on what is expected as input for a seamless experience.

Output in C++

Displaying output is critical for showing the results of computations or expressing program states. In C++, we often utilize the `cout` object from the `` library to print messages or variables to the console. For example, using `std::cout << "num1 = " << num1 << std::endl;` prints out the value stored in `num1` along with a descriptive message.
This approach lets users understand what the program is doing and allows them to verify correct operations. Using `std::endl` after each output ensures that each message or result appears on a new line, making your output clear and organized.

Basic Arithmetic Operations

Arithmetic operations form the backbone of most programs—they allow you to perform fundamental calculations and data processing. In C++, operations such as addition, subtraction, multiplication, and division can be executed directly using symbols like `+`, `-`, `*`, and `/`.
For instance, the expression `(2 * num1 - num2)` calculates twice the value of `num1` minus the value of `num2`.

• Multiplication is represented by `*`, and subtraction by `-`.

Such expressions can be part of more complex calculations. Remember to use parentheses to dictate the order of operations clearly and prevent logical errors.