Question

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

Short answer

cin >> x; cin >> y; i = 1; power = 1; power *= x; ++i; i <= y; cout << power;

Step-by-step solution

Inputting Integer Variable x

Use cin with the extraction operator (>>) to take an integer input from the user and store it in variable x: \(\operatorname{cin} >> x;\)

Inputting Integer Variable y

Similarly, use cin with the extraction operator to take another integer input from the user and store it in variable y: \(\operatorname{cin} >> y;\)

Initializing Integer Variable i

Set the integer variable i to 1: \(i = 1;\)

Initializing Integer Variable power

Set the integer variable power to 1, as the initial value for the power calculation: \(power = 1;\)

Updating Variable power

Multiply variable power by x and assign the result back to power: \(power *= x;\) This statement is a shorthand for \(power = power * x;\)

Preincrementing Variable i

Preincrement variable i by 1: \(++i;\) This means i will be increased by 1 before it is used in any other expression.

Comparing i with y

Use a comparison operator to determine if i is less than or equal to y: \(i <= y;\)

Outputting Integer Variable power

Use cout with the insertion operator (<<) to output integer variable power: \(\operatorname{cout} << power;\)

Key concepts

cin and cout in C++

In C++, cin and cout are part of the iostream library and stand for 'character input' and 'character output', respectively. They are used to read and write data from and to the standard input (like a keyboard) and output (like a console screen).

cin is used with the extraction operator (>>), which reads the input from the user and stores it in a given variable. For instance, cin >> x; takes an integer input from the user and assigns it to the variable x. It's important for students to ensure that the type of data they are inputting matches the type of the variable being used to avoid errors.

On the other hand, cout is used with the insertion operator (<<), which sends the variable's value to the standard output. To output an integer variable such as power, you would use cout << power;. Understanding these essential components of user interaction in C++ is crucial for anyone starting in C++ programming.

Variable Initialization in C++

Initializing variables in C++ is a fundamental concept that ensures variables begin with a specific value. Variable initialization means setting a variable to a well-defined value when it is created. For example, i = 1; initializes the integer variable i with the value 1.

Proper initialization helps prevent errors that may occur when variables are used without being set to a definite value, which could lead to unpredictable results. In C++, there are several ways to initialize variables:

• Copy initialization: int a = 10;
• Direct initialization: int b(10);
• Uniform initialization (C++11 onwards): int c{10};

Students should familiarize themselves with these methods and adopt the practice of initializing variables to avoid issues with garbage values and to make their code more readable and maintainable.

Arithmetic Operators in C++

Arithmetic operators in C++ are used to perform mathematical operations on variables and values. The fundamental arithmetic operators are addition (+), subtraction (-), multiplication (*), division (/), and modulo (%), which returns the remainder of a division operation.

Beyond these, C++ also supports compound assignment operators that perform an operation and assignment in one step, such as +=, -=, *=, and /=. For instance, the operation power *= x; multiplies power by x and then assigns the result back to power. It is equivalent to power = power * x;. Understanding arithmetic operators is essential for performing calculations and manipulating data in a C++ program.

Students should also note the use of the preincrement operator (++i), which increases the value of i by 1 before it is used in any expression, as opposed to the postincrement operator (i++), which increases the value after the expression is evaluated. Recognizing and applying these operators correctly can efficiently solve mathematical problems within a program.