Question

Simple Messages: Store a message in a variable, and print that message. Then change the value of your variable to a new message, and print the new message. Save each of the following exercises as a separate file with a name like name_cases.py. If you get stuck, take a break or see the suggestions in Appendix C.

Short answer

Store a message in a variable, print it, change the message, and print it again.

Step-by-step solution

Create a Variable and Assign a Message

Begin by choosing a simple message such as "Hello, world!" and store it in a variable named `message`. In Python, you assign a value to a variable by using the equal sign `=`. Type the following line in your Python file: ```python message = "Hello, world!" ```

Print the Initial Message

Next, you need to print the message stored in the variable. Use the `print()` function to display the message. Add the following line to your code: ```python print(message) ```

Update the Variable with a New Message

Change the value of the variable `message` to a new message, such as "Goodbye, world!". Replace the old message with the new one like this: ```python message = "Goodbye, world!" ```

Print the New Message

Finally, print the new message by calling the `print()` function again with the updated variable. Add the following line to your script: ```python print(message) ```

Key concepts

Understanding Variables in Python

Variables in Python are essentially containers that store data values. Think of them as labeled boxes where you can keep and access different types of information. This can be anything from numbers to text strings. When you want to create a variable, you give it a name like `message`, and then assign it a value using the equal sign `=`.

Here are some key points about variables in Python:

• They can hold different types of data, such as integers, floats, and strings.
• Variable names must start with a letter or underscore, followed by letters, digits, or underscores.
• Python is dynamically typed, which means you don't have to specify the data type of a variable when you create it.

For example, when you write:
```python message = "Hello, world!" ``` You create a variable named `message` and store the string "Hello, world!" in it.
Understanding how to properly name and assign values to variables is foundational for writing efficient code in Python.

Mastering the Print Function in Python

The `print()` function in Python is a built-in function that outputs data to the screen. It's one of the simplest yet most powerful functions you'll often use in programming.
Using `print()`, you can display the value of variables or direct expressions. This is particularly helpful for debugging and confirming that your code is working as intended.

Here's how you use the `print()` function:

• Simply write `print()` followed by the variable name or text you want to display inside the parentheses.
• The function automatically adds a newline at the end of each call, so each `print()` outputs data on a new line.
• You can print multiple items at once by separating them with commas.

So, the line: ```python print(message) ``` will display whatever current value is stored in `message`. Understanding how to use the `print()` function is crucial, especially for beginners, as it helps to track what your program is doing at different stages.

Updating Variables in Python

Updating variables means changing their value during the execution of a program. In Python, you can easily update a variable by assigning a new value to it using the `=` operator.

This process allows you to change the state of your program or respond to new conditions. Here's a quick guide on updating variables:

• Simply use the same variable name and assign a new value.
• Remember that the new value will overwrite the original value stored in the variable.
• This can be done as many times as needed during the program's execution.

For example: ```python message = "Goodbye, world!" ``` This line changes the original value of the `message` variable from "Hello, world!" to "Goodbye, world!". Understanding variable updates is essential, as many real-world applications rely on data that changes over time.