Identifiers are names given to variables, functions, classes, modules, and other objects in Python. They are used to uniquely identify these objects within a program. Python has specific rules for writing identifiers, which help ensure consistency and readability.
Rules for Writing Identifiers in Python:
- Start with a Letter or Underscore: Identifiers must begin with either a letter (a-z, A-Z) or an underscore (_).
- Consist of Letters, Digits, and Underscores: After the initial letter or underscore, identifiers can include letters, digits (0-9), and underscores.
- Case-Sensitive: Python is case-sensitive, meaning that
myVariableandMyVariableare treated as distinct identifiers. - Reserved Keywords: You cannot use Python's reserved keywords as identifiers. These keywords have special meanings in the language and cannot be used for other purposes. Examples include:
if,else,for,while,def,class, etc. - Meaningful and Descriptive: Choose identifiers that clearly indicate the purpose of the object they represent. This helps improve code readability and maintainability.
- Avoid Using Underscores at the Beginning: While underscores can be used within identifiers, it is generally recommended to avoid using them at the beginning of an identifier. Leading underscores can have special meaning in Python.
Examples:
- Valid Identifiers:
my_variable,age,total_count,_private_variable - Invalid Identifiers:
123variable,my-variable,if,class
By following these rules, you can write valid and meaningful identifiers in Python, contributing to clear, readable, and maintainable code.
