Variables in Python: Usage and Best Practices

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November 04, 2024
Variables in Python: Usage and Best Practices
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In Python, variables are symbolic names that refer to objects or values stored in your computer’s memory. They allow you to assign descriptive names to data, making it easier to manipulate and reuse values throughout your code.

Understanding variables is key for Python developers because variables are essential building blocks for any Python program. Proper use of variables allows you to write clear, readable, and maintainable code.

In this tutorial, you’ll learn how to:

  • Create and assign values to variables
  • Change a variable’s data type dynamically
  • Use variables to create expressions, counters, accumulators, and Boolean flags
  • Follow best practices for naming variables
  • Create, access, and use variables in their scopes

To get the most out of this tutorial, you should be familiar with Python’s basic data types and have a general understanding of programming concepts like loops and functions.

Don’t worry if you don’t have all this knowledge yet and you’re just getting started. You won’t need this knowledge to benefit from working through the early sections of this tutorial.

Take the Quiz: Test your knowledge with our interactive “Variables in Python: Usage and Best Practices” quiz. You’ll receive a score upon completion to help you track your learning progress:

Variables in Python

Interactive Quiz

Variables in Python: Usage and Best Practices

In this quiz, you'll test your understanding of variables in Python. Variables are symbolic names that refer to objects or values stored in your computer's memory, and they're essential building blocks for any Python program.

Getting to Know Variables in Python

In Python, variables are names associated with concrete objects or values stored in your computer’s memory. By associating a variable with a value, you can refer to the value using a descriptive name and reuse it as many times as needed in your code.

Variables behave as if they were the value they refer to. To use variables in your code, you first need to learn how to create them, which is pretty straightforward in Python.

Creating Variables With Assignments

The primary way to create a variable in Python is to assign it a value using the assignment operator and the following syntax:

Python Syntax 
variable_name = value

In this syntax, you have the variable’s name on the left, then the assignment (=) operator, followed by the value you want to assign to the variable at hand. The value in this construct can be any Python object, including strings, numbers, lists, dictionaries, or even custom objects.

Here are a few examples of variables:

Python 
>>> word = "Python"

>>> number = 42

>>> coefficient = 2.87

>>> fruits = ["apple", "mango", "grape"]

>>> ordinals = {1: "first", 2: "second", 3: "third"}

>>> class SomeCustomClass: pass
>>> instance = SomeCustomClass()

In this code, you’ve defined several variables by assigning values to names. The first five examples include variables that refer to different built-in types. The last example shows that variables can also refer to custom objects like an instance of your SomeCustomClass class.

Setting and Changing a Variable’s Data Type

Apart from a variable’s value, it’s also important to consider the data type of the value. When you think about a variable’s type, you’re considering whether the variable refers to a string, integer, floating-point number, list, tuple, dictionary, custom object, or another data type.

Python is a dynamically typed language, which means that variable types are determined and checked at runtime rather than during compilation. Because of this, you don’t need to specify a variable’s type when you’re creating the variable. Python will infer a variable’s type from the assigned object.

For example, consider the following variables:

Python 
>>> name = "Jane Doe"
>>> age = 19
>>> subjects = ["Math", "English", "Physics", "Chemistry"]

>>> type(name)
<class 'str'>
>>> type(age)
<class 'int'>
>>> type(subjects)
<class 'list'>

Read the full article at https://realpython.com/python-variables/ »

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November 04, 2024 at 07:30PM
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