Question

Write single \(C++\) statements that do the following: a. Input integer variable \(x\) with \(\operatorname{cin}\) and \(\gg>\) b. Input integer variable \(y\) with \(\operatorname{cin}\) and \(\gg>\) c. Set integer variable 1 to 1 d. Set integer variable power to 1 e. Multiply variable power by x and assign the result to power. f. Postincrement variable i by 1 g. Determine whether is less than or equal to \(y\). h. Output integer variable power with cout and \(<<\)

Short answer

Use `cin >> x; cin >> y; int i = 1; int power = 1; power *= x; i++; i <= y; cout << power;` for each operation in C++.

Step-by-step solution

Input of Variable x

To input the integer variable \( x \) using `cin`, we use the statement `cin >> x;`. This line of code takes input from the user and stores it in the variable \( x \).

Input of Variable y

Similarly, to input the integer variable \( y \) using `cin`, the statement `cin >> y;` is used. This reads the input from the user into the variable \( y \).

Initialize Variable i

To set the integer variable \( i \) to 1, you write the statement `int i = 1;`. This initializes \( i \) with the value of 1.

Initialize Variable power

Set the integer variable `power` to 1 using the statement `int power = 1;`. This assigns the initial value of 1 to the variable `power`.

Multiply Power by x

The multiplication of `power` by \( x \) and assignment back to `power` is done by the statement `power *= x;`. This line is equivalent to `power = power * x;`.

Postincrement Variable i

To postincrement the variable \( i \) by 1, use the statement `i++;`. This increases the value of \( i \) by 1, but after its current value is used in the expression.

Compare i with y

To determine if \( i \) is less than or equal to \( y \), use the logical expression `i <= y`. This evaluates to `true` if \( i \) is less than or equal to \( y \), and `false` otherwise.

Output Variable power

Output the integer variable `power` with `cout` using the statement `cout << power;`. This prints the value of `power` to the screen.

Key concepts

Input and Output in C++

In C++, input and output are fundamental operations that allow interaction with the user.
For input, we typically use the `cin` object, which stands for character input.
It reads data from the standard input device, usually the keyboard.
To input integers into variables, we use the extraction operator `>>`.
This operator takes the value entered by the user and assigns it to the specified variable.
For instance, to input a variable `x`, you would write `cin >> x;`.
It’s important to prompt the user for input beforehand, so they know what to enter. When it comes to output, we use the `cout` object, meaning character output.
This outputs data to the standard output device, typically the screen.
The insertion operator `<<` is used to send information to the output.
To output a variable `power`, you write `cout << power;`, which displays the value of `power` on the screen.

Variables and Initialization

Variables in C++ are used to store data that your program can manipulate.
Before you use a variable, you must declare it and, optionally, initialize it.
Declaring a variable informs the compiler of the variable's type and name.
Initialization gives it an initial value. For instance, the statement `int i = 1;` does two things:

• It declares `i` as an integer, indicating the type of data it can store.
• It initializes `i` with the value of 1, setting a starting point.

Similarly, `int power = 1;` initializes `power` to 1.
Initialization is crucial because uninitialized variables can hold unpredictable values.
This might lead to errors in your program if not handled properly. Always remember to choose meaningful variable names to make your code easier to understand.

Control Structures

Control structures in C++ are constructs that control the flow of execution.
They allow you to decide which lines of code are executed in specific situations.
One common control structure is the comparison or logical expression.
This is used to evaluate conditions and make decisions based on them.
The example `i <= y` checks if `i` is less than or equal to `y`.
If this condition is true, certain actions may take place based on the program's logic.
Comparison operators like `==`, `!=`, `>`, `>=`, `<`, and `<=` are the tools for making these decisions. In combination with control structures like `if` statements, they help control the execution flow.
These comparisons are essential in loops, conditionals, and many other structures in C++.
They provide the necessary flexibility to implement complex logic smoothly.

Loops and Iteration

Loops in C++ provide a way to execute the same block of code multiple times.
This is particularly useful for repeating operations, such as calculations, until a specific condition is met.
Two main types of loops are `for` loops and `while` loops.

• A `for` loop is often used when the number of iterations is known. It has a clear initialization, condition, and increment step.
• A `while` loop continues executing as long as a specified condition is true. It's executed when the number of iterations is unknown or dependent on dynamic conditions.

Postincrementing, such as `i++`, is common in loop structures.
It increases the value by one, after its current value is used in evaluations, providing a seamless transition to the next iteration. Combining these elements effectively allows programmers to handle repetitive tasks efficiently, manage resources, and streamline code execution.
Each loop type offers its advantages depending on the task requirements.