Question

Write a C++ statement that prints the message "The number is valid." if the variable temperature is within the range -50 through 150.

Short answer

Question: Write a C++ statement that checks if the value of a variable 'temperature' is within the range -50 through 150 and prints "The number is valid." if the condition is satisfied. Answer: ```if (temperature >= -50 && temperature <= 150) { std::cout << "The number is valid." << std::endl; }```

Step-by-step solution

Check the range

To verify if the value of the variable 'temperature' is within the range -50 through 150, use an if statement with a logical condition that checks if the value is greater than or equal to -50 and less than or equal to 150: ```cpp if (temperature >= -50 && temperature <= 150) ```

Print the message

If the condition in the if statement is satisfied, meaning that the value of the 'temperature' variable is within the given range, use a 'std::cout' statement inside the if statement block to print the message "The number is valid.": ```cpp std::cout << "The number is valid." << std::endl; ```

Final Solution

Putting the steps together, the final C++ code should look like this: ```cpp if (temperature >= -50 && temperature <= 150) { std::cout << "The number is valid." << std::endl; } ```

Key concepts

C++ Logical Operators

Logical operators in C++ are essential for making decisions based on multiple conditions. A logical operator will return a boolean value, that is, either true or false. In our original exercise, we used the logical "AND" operator, represented by `&&`. This operator checks if both conditions are satisfied simultaneously.

For example:

• `temperature >= -50` checks if the value of temperature is greater than or equal to -50.
• `temperature <= 150` checks if the value of temperature is less than or equal to 150.

The `&&` operator combines these two conditions to ensure both are true. Thus, the full condition `temperature >= -50 && temperature <= 150` verifies that the temperature lies within the specified range from -50 to 150. Understanding how logical operators function is crucial for constructing complex logical expressions in C++.

C++ Input/Output

In C++, the standard library provides several ways to handle input and output, crucial for interacting with users and displaying results. For output operations, such as displaying messages to the user, we use the `std::cout` stream, which stands for 'standard character output'.

Here are some key points about `std::cout`:

• It is used with the insertion operator `<<` to send data to the standard output, typically the computer screen.
• Statements are often terminated with `std::endl`, which inserts a new line and flushes the output buffer, ensuring that all the data sent to the output is displayed immediately.
• It belongs to the `iostream` library, which you must include in your program using `#include `.

In the original exercise, `std::cout << "The number is valid." << std::endl;` is used to output the message when the temperature meets the specified conditions. Mastering input and output operations in C++ enables you to efficiently manage user interactions and results presentation.

Conditional Statements in C++

Conditional statements in C++ are the backbone of decision-making in programs. They allow code to execute different actions based on specific conditions. The simplest form is the `if` statement.

The `if` statement consists of a condition and a block of code that runs only if the condition evaluates to true. In our exercise, we utilize a condition that determines if a variable, `temperature`, falls within a defined range (-50 to 150): ```cpp if (temperature >= -50 && temperature <= 150) ``` If the condition is true, the following block executes: ```cpp { std::cout << "The number is valid." << std::endl; } ``` Key features of conditional statements include:

• They are crucial for controlling the flow of a program based on dynamic variables and states.
• When the condition is false, the block inside the `if` statement is skipped, and the program continues execution with subsequent statements.

Understanding conditional statements is fundamental for creating responsive and intelligent C++ programs that can perform different actions under various circumstances.