Variables in Python

Welcome back! Now that you’ve set up your development environment with VSCode and written your first Python program, it’s time to dive deeper into the language itself. Today, we’ll explore one of the fundamental concepts in programming: variables. Understanding variables is crucial because they allow us to store and manipulate data. Let’s get started!

What is a Variable?

A variable is like a container that holds data. This data can be anything from a number to a string of text. In Python, you don’t need to declare the type of a variable explicitly. Python is dynamically typed, which means the type of a variable is determined at runtime based on the value assigned to it.

Declaring Variables

In Python, you declare a variable by simply assigning a value to it using the equals sign (=). Let’s look at some examples:

# Integer variable
age = 25

# Float variable
price = 19.99

# String variable
name = "Alice"

# Boolean variable
is_student = True

In these examples, we’ve created four variables: age, price, name, and is_student. Each variable holds a different type of data.

Variable Naming Rules

When naming variables in Python, there are a few rules you should follow:

1. Must start with a letter or an underscore: You cannot start a variable name with a number.
2. Can contain letters, numbers, and underscores: After the first character, you can use letters, numbers, and underscores.
3. Case-sensitive: Variable names are case-sensitive, so age and Age are considered different variables.
4. No spaces: Use underscores to separate words (e.g., first_name instead of first name).

Assigning Values to Variables

You can assign values to variables using the assignment operator (=). You can also update the value of a variable after it has been declared:

# Assign a value to a variable
score = 90

# Update the value of the variable
score = 95

print(score)  # Output: 95

In this example, we initially assign the value 90 to the variable score, and then we update its value to 95.

Multiple Assignments

Python allows you to assign values to multiple variables in a single line. This can make your code cleaner and more concise:

# Assign values to multiple variables
x, y, z = 5, 10, 15

print(x)  # Output: 5
print(y)  # Output: 10
print(z)  # Output: 15

In this example, we assign the values 5, 10, and 15 to the variables x, y, and z, respectively.

Swapping Variables

Swapping the values of two variables is straightforward in Python. You can do it in a single line using tuple unpacking:

a = 1
b = 2

# Swap the values
a, b = b, a

print(a)  # Output: 2
print(b)  # Output: 1

Here, the values of a and b are swapped in one line.

Example: Using Variables in a Program

Let’s put our knowledge of variables into practice with a simple program that calculates the area of a rectangle:

# Define the dimensions of the rectangle
width = 5
height = 10

# Calculate the area
area = width * height

# Print the result
print("The area of the rectangle is:", area)

In this program, we use variables width and height to store the dimensions of the rectangle. We then calculate the area by multiplying these two variables and store the result in the area variable. Finally, we print the result.

Conclusion

Variables are a fundamental concept in programming, and they are used to store and manipulate data. In Python, you can declare variables by simply assigning a value to them, and you can update their values as needed. Remember to follow the variable naming rules to ensure your code is readable and error-free.

Now that you understand variables, you’re ready to move on to more advanced topics. In our next tutorial, we’ll explore data types in Python. Stay tuned, and happy coding!