What is Variable in Python: A Comprehensive Guide to Efficient Coding

A variable is basic to Python. It works as a storage block where data can be stored, along with its name. Variables may be viewed as entities that have the capacity to store various types of data that our programs can subsequently process. Understanding what is variable in Python and how to use it efficiently enables one to handle data comprehensively. For instance, instead of typing the same value every time it is needed, we just represent it once and then type the representation every time it needs typing.

Also, Python does not need us to declare the kind of variable we wish to use, unlike the majority of other languages. We only enter a value, and Python does the rest for us. This is not only time-saving but also makes our code neat and clean, hence easy to debug and modify. The said simplicity makes Python one of the most suitable languages for programming, whether for first-timers or professional developers.

Creating and Assigning Values to Variables

Creating a variable in Python is pretty easy. It is just a convenient way to select a name, make it stand for something, and then use the equals sign to make the assignment. This procedure is referred to as variable assignment.

Example:

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In this example, name and age are variables through which results can be obtained. The code illustrates how one can assign values to variables and then use these variables in further code execution.

Here are the primary data types:

• Integer (int): Whole numbers without a decimal point.
• Float (float): Numbers with a decimal point.
• String (str): A sequence of characters.
• Boolean (bool): Represents True or False.
• List (list): An ordered collection of items.
• Tuple (tuple): An immutable ordered collection of items.
• Dictionary (dict): A collection of key-value pairs.
• Set (set): An unordered collection of unique items.

Rules and Best Practices for Naming Variables in Python

Naming variables appropriately is crucial for code readability and maintenance. Python has some rules and best practices for naming variables:

• Variable names must begin with a letter or an underscore.
• Variable names should contain only letters (a-z, A-Z), digits (0-9), and underscores.
• Python variable names are case-sensitive. This means that the names “age” and “Age” are treated differently.
• Keywords like False, True, None, and, or, not, etc., cannot be used as variable names.

Examples of valid variable names:

• my_variable = 10
• _variable = “underscore”
• var123 = 5.67

Examples of invalid variable names:

• 1st_variable = 10 (Cannot start with a digit)
• my-variable = 20 (Hyphens are not allowed)
• class = “Python” (‘class’ is a reserved keyword)

Reassigning Variables in Python

Variables defined in Python can be reassigned, which basically means that one can modify the value or type of a variable once it has been created.

Example:

Code Example with User Input

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Performing Multiple Assignments in Python

Multiple assignment in Python is one way to assign various values to variables in a single step. This feature is useful for assigning values for more than one variable in one line. This ability of Python helps create more organized and easy-to-read codes.

For instance, instead of writing:

• a = 1
• b = 2
• c = 3

we can do this in one line:

• a, b, c = 1, 2, 3

This is not only shorter but also cleaner.

Example with User Input

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Global vs. Local Variables in Python

We can divide the variables in Python into two sections namely Global Variables and Local Variables. Let’s understand both with suitable examples.

Global Variables

Global variables are declared outside a function and are accessible at all levels of the program.

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Local Variables

Local variables are created inside a function and cannot be accessed in any other part of a program.

Example:

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If we try to access y outside the function, we’ll get an error because y is a local variable.

Example with User Input

Let’s create a function that uses both global and local variables, incorporating user input.

Output:

This example shows the difference in behavior between global and local variables, highlighting their scopes.

Modifying Global Variables Using the Global Keyword

Sometimes, we need to modify a global variable inside a function. For this, we use the global keyword. It allows us to update the global variable from within the function.

Example:

Output:

In this example, we see how the global keyword allows us to modify the global variable x within the function.

Understanding Memory Management and Object References

Python comes with memory management capabilities built in. This basically implies that when we declare a variable, the Python interpreter reserves a place in the computer’s memory for that variable.

In Python, a variable is an object that has a reference to another object in memory. This implies that when we assign one variable to another, they will both point to the same object.

Example Code

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Arithmetic Operations with Python Variables

Arithmetic operations are basic operations in every programming language, including Python.

Addition

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Subtraction

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Multiplication

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Division

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String Operations with Python Variables

In Python, strings are unique and can be handled in various forms. They are employed to manage text that may be words, sentences, or even paragraphs.

Concatenation

Combining two or more strings is called concatenation. We can do this using the + operator.

Example:

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Slicing

Slicing allows us to extract a portion of a string. We specify the start and end indices.

Example:

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Formatting

String formatting is useful for inserting variables into strings. We use f-strings for this purpose.

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Immutability

We cannot change a string in Python after creation; this is called immutability. Instead, we can create new strings.

Example:

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Deleting Variables in Python

Sometimes, we need to delete variables to free up memory or remove them from the scope. We use the del statement for this purpose. Deleting variables helps in managing memory, especially when dealing with large datasets or temporary data.

Example:

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Conclusion

In this blog, we explored the world of Python variables. We learned what variables are in Python, how to declare and define variables with values, learned about value types and best practices in choosing the names of variables. Next, we learnt about changing the reference of variables, doing multiple assignments, and the differentiation between global and local variables. We also understood the string operations and memory management using the deletes statement. Understanding these key concepts enhances the coding ability and efficiency of any coder who is using Python language.