Home

Learning Hub

Articles

Identifiers in Python – Explained With Examples

An identifier is a term in the Python programming language used to name entities such as variables, functions, classes, modules, and more. Understanding identifiers is crucial for writing, reading, and maintaining code. In this article, we will explore identifiers and their rules. Let’s get started!

What are Identifiers?

An identifier is used to name a variable, class, module, function, or any other element within code. Identifiers are used to name variables in computer programming languages. It helps programmers to identify and differentiate them from other entities.

Here’s is Identifier example

What is an Identifier in Python?

In the Python language, an Identifier is a name used to define a variable, function, class, or module. An identifier contains only letters, digits, and underscores. It cannot start with a digit. In Python, identifiers are case-sensitive, meaning that Ram and Ram are considered to be two different identifiers.

Example of Python Identifiers

The following program demonstrates a simple example of Python Identifiers

Program

Output

Rules for Identifiers in Python

Defining the identifiers is very important. Good identifiers can be identified easily in source code and used easily.

• There is no restriction on the length of identifiers.
• Identifier in Python is case-sensitive
• Special symbols like !,@,#,%, etc. Are not allowed in identifiers.
• You cannot define the reserve keywords as the identifier, they have special meaning in the Python language.
• An identifier cannot start with a digit. If it starts with a digit, it will give a Syntax Error in the Python language.
• An identifier is a combination of character digits and underscore. Characters include lowercase and uppercase with 0 to 9 digits and underscore.

These are some examples of valid identifiers in Python language.

These are some valid identifiers in the Python language.

Always follow these practices for defining the Identifier in Python language:

• Use descriptive names: Write names that clearly convey the purpose or meaning of the identifier. This enhances code readability and makes it easier for other developers to understand your source code.
• Use snake_case: In the Python language, it is recommended that variables, functions, and methods be named using snake_case instead of cameCase or PascalCase.
• Limit the Length of Names: Names should be short and concise in Python when you are defining the identifier. But not too short to the point of being ambiguous.
• Avoid Single-Letter Variable: In Python language, It is good practice to avoid using single letters variable names except for temporary variables in Python language.

Testing the Validity of Python Identifiers

The str.isidentifier() function is used in Python to check the validity of an identifier, but this method does not take reserved keywords. It returns true if this is a valid identifier; if it is not valid, it returns false.

The following program demonstrates the Testing Valid Identifiers in Python language.

Program

Output

Invalid Identifiers Example

Here are some examples of Invalid Python Identifiers.

• 123abc
• abc@
• 123
• for

Python Keywords

There are 36 keywords in the Python language. The following table describes all 36 Python keywords.

Difference Between Identifiers and Keywords

The following table differentiates Identifiers and Keywords in the table.

Conclusion

In this article, we have learned about the Identifiers in the Python language. Identifiers are words that help developers define the names of variables, function modules, and classes. Identifiers have some rules to define them. Defining the identifiers within rules and best practices makes understanding and collaborating on the Python program easier.