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Identifier in Python

In computer programming, an identifier is a name given to a variable, function, class, module, or other objects in the code. The rules for creating valid identifiers vary depending on the programming language, but typically they must start with a letter or underscore and consist of only letters, digits, and underscores. Some programming languages have restrictions on the length of identifiers, here we discuss the identifiers in python, rules for identifiers in python, and valid and invalid identifiers in python. Some have specific reserved words that cannot be used as identifiers. For example, in Python, "class" is a reserved word and cannot be used as identifiers in python

What is Identifier?

The name given to a variable, class, module, function or other object in the code is called an identifier. They are used to represent and refer to program elements. Starting with a letter or underscore, followed by letters, underscores, or digits, and avoiding reserved words are the rules for naming an identifier in Python. Identifiers must also be unique and meaningful, as they aid in the readability and comprehension of code. They are case-sensitive, so "variable" and "Variable" are treated differently. Identifiers can have a local or global scope, which determines their program accessibility.

What is Identifier in Python?

Identifiers in Python is a names used to identify a variable, function, class, module, or other objects. An identifier can only contain letters, digits, and underscores, and cannot start with a digit. In Python, identifiers are case-sensitive, meaning that foo and Foo are considered to be two different identifiers.

Examples of Python Identifiers

Here we have some examples of valid and invalid identifiers in python

Valid Identifiers
These are examples of valid identifiers in python.

  • yourname It contains only lowercase alphabets.
  • Name_school It contains only ‘_’ as a special character.
  • Id1 Here, the numeric digit comes at the end.
  • roll_2 It starts with lowercase and ends with a digit.
  • _classname Contains lowercase alphabets and an underscore and It starts with an underscore ‘_’

Invalid Identifiers
These are examples of valid invalid identifiers in python.

  • (for, while, in)These are the keywords in python that cannot use as identifiers in python.
  • 1myname Invalid identifier because It begins with a digit
  • \$myname Invalid identifier because It starts with a special character
  • a b Invalid identifier because it contains a blank space
  • (a/b and a+b) are Invalid identifiers because contain special character

Rules for Identifiers in Python

These are the rules for identifiers in python

  • Keywords cannot be used as identifiers in python (because they are reserved words)
  • The name of identifiers in python cannot begin with a number
  • All the identifiers in python should have a unique name in the same scope
  • The first character of identifiers in python should always start with an alphabet or underscore, and then it can be followed by any of the digit, character, or underscore.
  • Identifier name length is unrestricted
  • Names of identifiers in python are case sensitive meaning ‘car’ and ‘Car’
  • Would be treated differently
  • Special characters such as ‘%’, ‘#’,’@’, and ‘$’ are not allowed as identifiers in python.

Python Identifier Naming

When naming identifiers in python, it is recommended to follow these best practices:

  • Use descriptive and meaningful names: names should accurately describe the purpose of the identifier, and make it easy to understand the code.
  • Use snake_case: in Python, it is recommended to use snake_case instead of camelCase or PascalCase for naming variables, functions, and methods.
  • Avoid using Python keywords: keywords like if, else, def, etc. cannot be used as names for identifiers.
  • Avoid using abbreviations: abbreviations can make the code harder to read and understand.
  • Limit the length of names: names should be short and concise, but not too short to the point of being ambiguous.
  • Use consistent naming conventions: be consistent in your naming conventions throughout the codebase to improve readability and maintainability.
  • Identifiers in python should be descriptive and meaningful. For example, "x" is not a good variable name, but "student_name" is more informative.
  • Identifiers in python should be lowercase and use underscores to separate words. This convention is known as show_case.
  • It is not recommended to use special characters and spaces in an identifier name.
  • It’s a good practice to avoid using single-letter variable names except for temporary variables in python
  • Some library/module names also follow the same naming conventions, it is a good practice to follow the same for your identifier.

Python is a high-level programming language that provides a rich set of features for creating readable and maintainable code. One important aspect of writing Python code is to use meaningful and descriptive names for variables, functions, classes, and other objects in the code. These names are called identifiers in Python.

  • Identifiers must start with a letter or an underscore.
  • Identifiers can only contain letters, numbers, and underscores.
  • Python is case-sensitive, so "Myname", "myname" and “MYname” are considered to be different identifiers.
  • Python has a set of reserved words that cannot be used as identifiers. Some of these reserved words include ‘for’, ‘while’,’pass’, ‘in’.

Identifiers cannot be the same as any Python built-in functions or modules. For example, "print" is a built-in function in Python, so it cannot be used as an identifier.

Frequently Asked Questions(FAQ)

Here are the some frequently asked questions and answers on identifiers in python the question-and-answer form:

Question 1: What is identifier in python
Answer: Python identifiers are the names given to variables, functions, classes, modules, etc. in Python.

Question 2: What are the rules for naming a Python identifier?
Answer: To name a Python identifier, the following rules must be followed:
The name must start with a letter or an underscore, followed by zero or more letters, underscores, or digits.
Python is case-sensitive, so "variable" and "Variable" are considered different.
A set of words that have special meaning in Python cannot be used as identifiers, such as "if", "else", "for", etc.

Question 3: What is the maximum length of a Python identifier?
Answer: There is no maximum length for a Python identifier, but it is recommended to keep it short and meaningful.

Question 4: Can Python identifiers start with a number?
Answer: No, Python identifiers cannot start with a number. They must start with a letter or an underscore.

Question 5: What is the difference between a local and a global identifier in Python?
Answer: In Python, a local identifier is defined inside a function and has a local scope, meaning it can only be accessed within that function. A global identifier, on the other hand, is defined outside a function and has a global scope, meaning it can be accessed from anywhere in the code.

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