Question

Write an if statement that displays the message "The number is valid" if the value referenced by speed is within the range 0 through 200 .

Short answer

Question: Write an if statement to check if the value of a variable 'speed' is within the range of 0 through 200 and display the message "The number is valid." Answer: To verify if the value of 'speed' is within the range of 0 to 200 and display a message, use the following if statement: ```python if 0 <= speed <= 200: print("The number is valid") ```

Step-by-step solution

Define the variable 'speed' with a sample value

First, let's assign a sample value to the variable 'speed' which we'll check later on. For example: speed = 150 Remember to replace the sample value with the actual value you want to validate. Step 2: Write an if statement to check the range

Write the if statement

Now we create an if statement with the specified condition (0 <= speed <= 200). If the condition is met, we print the message "The number is valid". The code will look like: if 0 <= speed <= 200: print("The number is valid") Ensure proper indentation for the 'print' statement. It should be indented inside the if statement. This solution checks whether the given value of 'speed' falls within the desired range and prints a corresponding message if it does.

Key concepts

Conditional Statements in Python

Conditional statements are the backbone of decision-making in Python programming. They allow the program to evaluate a condition and then perform different actions based on whether the condition is true or false. The simplest form is the 'if' statement, which has the basic structure:

if condition:
action

When the 'condition' evaluates to true, the 'action' block is executed. Otherwise, the action is skipped. Python also supports 'elif' (else if) for multiple conditions and 'else' for defining an action when all previous conditions fail.

It's crucial to note that Python uses indentation to define which lines of code are controlled by the if, elif, or else clauses. If you forget to indent, Python will not know which code to execute conditionally, and you'll likely encounter an 'IndentationError'.

To further understand the concept, consider the given exercise where we check the value of 'speed' against a range. The if statement is used to validate whether 'speed' meets the specified condition (0 <= speed <= 200). This demonstrates a basic yet powerful use of conditional statements in Python.

Range Validation

Range validation is an essential concept in Python, particularly when dealing with input or parameters that must fall within specific bounds. It's a way of ensuring that a value lies within a predefined interval, such as within 0 through 200 for a 'speed' variable.

To perform range validation using an if statement in Python, you can employ comparison operators (like <, >, <=, >=) to check if the value meets both the lower and upper bounds of the range:

if lower_bound <= variable <= upper_bound:

This single line of code can replace multiple lines that check each bound separately, thereby making your code more concise and readable. Keep in mind though, that the variable compared should be of a compatible data type (e.g., int, float) with the bounds.

Range validation is crucial in many programming scenarios, such as ensuring speed limits are adhered to in a simulation, limiting user input for dates, or enforcing minimum and maximum values for settings. It's a fundamental tool in your programming arsenal to maintain data integrity and prevent errors or unexpected behavior in your programs.

Python Programming Basics

Mastering Python programming basics forms the foundation for becoming a proficient Python coder. Starting with variables, you must understand how to declare them and assign values. In Python, variables are dynamically typed, meaning that you don't need to explicitly declare the data type; the interpreter infers it from the assigned value.

speed = 150

In the given exercise, 'speed' is a variable whose value is being checked against a range using a conditional statement. Other programming basics include knowledge of data types, operators, looping constructs, functions, and proper code structure and indentation. Python's syntax is designed to be clean and readable, with a strong emphasis on avoiding unnecessary complexity.

Lastly, always remember to test your code with different input values, handle possible exceptions, and follow best practices in naming variables and structuring your code. These fundamental skills, used in writing the exercise's if statement, are the stepping stones towards tackling more complex programming tasks in Python.