Is Python Case Sensitive When Dealing with Identifiers?

Yes, Python is a case-sensitive programming language. Python sees the lowercase and uppercase letters differently. Being a high-level and dynamic language, it asks the users to avoid using the same name in different cases while naming identifiers. Web development, data analysis, machine learning, and scripting are a few examples of what tasks can be achieved using Python programming language.

In this article, we will go through in detail how is Python case-sensitive when dealing with identifiers. We will see the rules for identifiers and naming conventions, in this article, along with the best practices that a Python developer should follow while creating a program or developing an application.

What is Python?

Python stands as a high-level programming language — not to mention a powerful one — that offers effective high-level data structures and an uncomplicated introduction to the object-oriented paradigm. While Python is recognised for its easy-to-understand syntax, it also excels in the world of object-oriented programming effectiveness and dynamic typing.

Rules for Identifiers in Python

Python, being a popular programming language amongst current-time developers and programmers, has its own set of rules or grammar to name its identifiers. These rules help in easily identifying different variables, names, functions, etc., between hundreds and thousands of items. They are essential for writing clear and maintainable code.

Specific guidelines about character usage, letter case, capitalisation, and reserved words must be adhered to when naming identifiers in Python. Here are some of the common and significant rules to be followed while naming identifiers in Python:

• Keyword restriction: Python consists of various reserved keywords like while, for, if, etc., therefore don’t use these reserved words while naming an identifier.
• Case Sensitivity: Identifiers are case sensitive; therefore, words like ‘Hello’, ‘hello’, and ‘HELLO’ are all treated differently, so always keep them in mind.
• Alphabetic and Numeric Characters: While naming an identifier in Python, it can contain letters (from a-z or A-Z), digits (0-9), and underscores (_).
• Beginning character: The beginning of a character cannot start either with an underscore (_) or a digit. For example, _hello or 3hello both are invalid identifiers.
• No leading digit: An identifier cannot start with a digit while naming its identifier. For example, ‘3isNumber’ is not a valid identifier in Python. If done, you will see an error.
• Length: In Python, there is no limit provided explicitly, but to have better readability and understanding, it is advised to keep the identifiers in short length;

Naming Identifiers in Python

Naming identifiers is a crucial step, as Python is a case-sensitive language. This indicates that the language makes a difference between characters used in identifiers that are capital and lowercase. While naming identifiers, certain conventions are to be followed in Python:

1. For Variables

To define the variables in Python, there is a certain naming convention that needs to be followed. For example, to define:

• Constant variable
  Constants are variables that are intended to be immutable and should not be changed throughout the program. By convention, constant variable names are written in all uppercase letters with words separated by underscores.

For example:
MAX_LIMIT = 100

VAL_PI = 3.14

• Global variable
  Global variables are variables that are available across a module or script and are defined at the top level of the module. Global variable names are often written in lowercase letters with underscores between words. For global variables, some developers do, however, also utilise CamelCase or mixed case.

For example:

global_var = “hello world”

path = “C://disk”

• Private variable

Private variables shouldn’t be accessible directly from outside of the class or module in which they are defined; instead, they should only be utilised within it. Private variable names often begin with a single underscore. To prevent name conflicts in subclasses, a double underscore can be utilised, resulting in name mangling, if greater privacy is required.

For example:

_my_private_variable

2. For Functions

Functions in Python are defined using lowercase words separated by underscores. This is known as snake_case. Functions in Python are not like other high-level programming languages including Java, C++, JavaScript, etc.

Example:

def find_area(radius_circle):

return 2 * 3.14 * radius_circle

def get_input():

user_in = input(“Enter the radius: “)

return user_in

3. For class names

Python class names adhere to the CapWords convention, which is also referred to as PascalCase or CamelCase. According to this standard, words are concatenated without any separators, and their initial letter is capitalised (like Aa).

Example:

class MyClass:

def _init_(self, val):

self.val = val

class ParentClass:

def _init_(self, value):

self.value = value

4. For packages

Python package names must be written entirely in lowercase characters. Although they are usually avoided, underscores (_) might be used if necessary to improve readability. It’s also typical to give packages brief, snappy names.

Example:

math

pip

Also Read: lambda function in python

Examples of Python Identifiers

Now that we have learned the naming convention and rules for identifiers in Python. To have a better understanding, let’s see some of the examples of valid and invalid identifiers in Python:

Valid Identifiers

1. my_count: This variable contains only letters in lowercase; therefore, it is valid.
2. my_count_1: This variable contains letters of lowercase along with the digits; therefore, it is valid.
3. _: This variable contains only underscore; therefore, it is valid.
4. _89: This variable contains only digits and is not a leading character; therefore, it is valid.
5. MyValid: This function contains letters of lowercase and uppercase; therefore, it is valid.
6. _my_private: This variable contains only letters in lowercase and underscore; therefore, it is valid.
7. MAX_LIMIT: This variable contains only letters in uppercase; therefore, it is valid.

Invalid Identifiers

1. 8count: This variable is leading from a digit; therefore, it is invalid.
2. 4000: This variable contains only digits; therefore, it is invalid.
3. p+q: This variable contains special characters; therefore, it is invalid.
4. while: This variable is a reserved word or keyword; therefore, it is invalid.

Common Pitfalls and How to Avoid Them

Notwithstanding its advantages, case sensitivity can sometimes result in some typical mistakes, particularly for inexperienced users. It’s essential to comprehend these traps and know how to avoid them to program Python effectively.

1. Typographical errors: Typographical errors are among the most frequent errors related to typos, incomplete words, incomplete characters, etc. Unintentionally employing the incorrect case can result in NameError errors. For example:

myName = “Hello World”

print(myname)

# Output: NameError: myname is not defined

2. Inconsistent Meaning: Confusion and difficulty reading and maintaining the code might result from inconsistent naming. Like if you have already defined a function name with some convention and later you used some other function name, it will result in an error and imply inconsistency. For example:

def findArea():

check

def findarea():

check

In the given example, it is confusing which code is valid and which is not. So, always follow Python’s PEP-8 naming conventions.

3. Shadowing: Shadowing may be seen when you use those identifiers that differ only in the case of built-in Python functions or keywords, and they can cause unexpected behaviour. For example:

list = [‘A’, ‘B’, ‘C’]

List = list  # It is called an unintended shadowing

4. Refactoring issues: Sometimes, programmers tend to refactor some parts of code, like refactoring a function name may result in an error. For example:

def findArea():

pass

def find_area():

pass

findArea()

# Output: NameError: name findArea is not defined

In this example, we have refactored the function findArea() with another function name. Now when we try to call this function with its original name, it will give us a name error (NameError).

Conclusion

In this article, we have seen that Python is case-sensitive when dealing with identifiers. We saw when naming an identifier, we have to follow and adhere to some rules of identifiers in Python, so that code becomes clear, readable, maintainable, etc. Naming identifiers for defining global, private, and constant variables, functions, class names, etc, were also discussed in this article. Python’s case sensitivity can be efficiently utilised by developers to construct legible and resilient programs by adhering to best practices, avoiding common errors, and keeping context in mind.