Question

Write C++ statement(s) that accomplish the following: a. Declare int variables x and y. Initialize x to 25 and y to 18. b. Declare and initialize an int variable temp to 10 and a char variable ch to 'A'. c. Update the value of an int variable x by adding 5 to it. d. Declare and initialize a double variable payRate to 12.50. e. Copy the value of an int variable firstNum into an int variable tempNum. f. Swap the contents of the int variables x and y. (Declare additional variables, if necessary.) g. Suppose x and y are double variables. Output the contents of x, y, and the expression x + 12 / y - 18. h. Declare a char variable grade and set the value of grade to 'A'. i. Declare int variables to store four integers. j. Copy the value of a double variable z to the nearest integer into an int variable x.

Short answer

Initialize variables, perform arithmetic, swap, and output in C++ effectively. Follow steps for accurate programming syntax.

Step-by-step solution

Variable Declaration and Initialization

Start by declaring the necessary integer variables. Use the statement: `int x = 25, y = 18;` This declares two integer variables, `x` and `y`, and initializes `x` to 25 and `y` to 18.

Declare Additional Variables

Declare another int variable `temp` and initialize it to 10, along with a char variable `ch`, initialized to 'A'. Use the statement: `int temp = 10; char ch = 'A';`.

Updating the Value of x

Increment the value of `x` by 5. The statement for this would be: `x = x + 5;` or alternatively `x += 5;`.

Declare a Double Variable

Declare and initialize a double variable `payRate` to 12.50 using the statement: `double payRate = 12.50;`.

Copy Integer Value

Copy the value of an existing integer variable `firstNum` into another integer variable `tempNum`. The statement for this is: `tempNum = firstNum;` assuming `firstNum` has been declared and initialized elsewhere in the code.

Swap x and y

To swap the values of `x` and `y`, you might declare a temporary variable. Use these statements: `int swapTemp = x; x = y; y = swapTemp;`.

Output for Double Variables

Assuming `x` and `y` are double variables, output their values and the expression mentioned: `cout << x << " " << y << " " << (x + 12 / y - 18) << endl;`.

Declare a Character Variable

Declare a char variable named `grade` and initialize it to 'A' with the following statement: `char grade = 'A';`.

Declare Multiple Integer Variables

Declare four integer variables in a single line. This can be done with: `int a, b, c, d;`.

Convert Double to Integer

Assuming `z` is a declared and initialized double variable, round its value and store it into `x`: `x = static_cast(round(z));` utilizing the `round` function to achieve rounding.

Key concepts

Variable Declaration

When you begin programming in C++, one of the first concepts you encounter is variable declaration. Declaring a variable means you are defining its data type and giving it a name so that it can be used in your program. Think of it like setting up a container to store specific types of information. In C++, you declare a variable with a statement like `int x;`, where `int` is the type of variable, and `x` is its name.

• The data type determines the kind of values the variable can hold, such as integers, floats, characters, etc.
• The variable name should be descriptive so that it is easy to understand what data it holds.

Remember, declaring a variable does not assign it a value. That process is called initialization, which we will discuss later. Without initialization, most variables just contain garbage values.

Integer Variables

Integer variables are among the most common data types used in C++. They store whole numbers without any decimal points, such as 1, -3, or 42. When you declare an integer variable, you use the `int` keyword followed by the variable name, like `int number;`.

• They are useful for counting and storing data that doesn't require decimal precision.
• If you need a larger range of values, C++ also provides types like `long` and `short` for extended integers.

For example, if you need two integer variables `x` and `y` set to 25 and 18 respectively, you would write: ```cpp int x = 25, y = 18; ``` This not only declares `x` and `y` as integer variables but also initializes them with specific values.

Variable Initialization

Initialization is the first assignment of a value to a variable. Initialization is crucial because, without it, you might end up using uninitialized variables that have unpredictable behaviors since they may contain garbage values from memory. In C++, initialization can be done at the time of declaration. For instance, to declare and initialize an integer variable `temp` with the value 10, you would write: ```cpp int temp = 10; ``` For variables of different types, the syntax is generally similar: - Characters: `char grade = 'A';` - Doubles: `double payRate = 12.50;` This practice not only makes your code cleaner but reduces the risk of errors from using uninitialized variables. Additionally, initializing variables as you declare them can make your programs easier to read and maintain.

Double Variables

Double variables in C++ are used to store floating-point numbers, which are numbers with decimal points. This is useful when precision and large ranges of values are needed. To declare a double variable, you use the `double` keyword followed by the variable name, like `double salary;`.

• Doubles can hold larger and more precise numbers than `float`, another floating-point data type.
• They are particularly useful in mathematical calculations or when working with currency, measurements, and scientific data.

To declare and initialize a double variable called `payRate` with a value of 12.50, the syntax would be: ```cpp double payRate = 12.50; ``` Using doubles ensures that you can perform accurate calculations when dividing two numbers or expressing a number's precision is essential, such as in physics simulations or financial calculations.