Is python case sensitive when dealing with identifiers?

Safalta Expert Published by: Aryan Rana Updated Mon, 12 Sep 2022 12:17 AM IST


A variable, function, class, module, or other object is known by its name when it is referenced in Python. An identifier often consists of one or more letters, underscores, or numerals from A to Z, or from a to z, followed by zero or more of those characters (0 to 9).

Python does treat uppercase and lowercase characters differently because it is a case-sensitive language. This also holds true for identifiers. Because of this, you must be careful when naming identifiers to prevent using the same name in several contexts. Always choose names that are simpler to understand. Instead of calling your variables C and c, you should name them count1 and count2 if you wish to keep counts of two values.


The latter would provide you with distinct variables, but over time, it might make things harder to grasp.  If you are interested in Digital Marketing or Graphic Designing and want to learn these interesting courses then click on the links mentioned Digital Marketing Course and Graphic Designing course

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Python Identifiers: Rules

A few conditions need to be satisfied in order to generate a Python identifier.
  • Identifier names cannot contain reserved keywords (special words used for a particular purpose, such as while, for, if, etc.).
  • Lowercase characters (a–z), capital letters (A–Z), numbers (0–9), and underscores (_) are all permitted in Python IDs.

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    As a result, Python identifiers can only contain the underscore special character.
  • No number may start with the name of the identifier.
  • A Python identifier's name may start with an underscore.
  • The identifier name's length is unconstrained.
  • Python identifier names are case-sensitive.

Python identifier example

You can generate identifiers in Python by using the aforementioned rules. Consider the following instances to get a better understanding of this:

Valid Identifiers

only includes letters and digits in count 1
contains all sane characters in count oddNo
_: an acceptable identifier is underscore
_count: identification may begin with an asterisk
_5: legitimate because it begins with an underscore and contains characters that are allowed.
My Dog Loves Cookies, Ham, and Cheese is still acceptable despite its length because there are no length limitations.

Invalid Identifiers

no keywords permitted for
A+B: Only underscores and other special characters are permitted.
200: An identification cannot be solely a number
Identifiers cannot start with numbers, according to 2Abs.

Best Practices for Python Identifier Naming

  • When naming identifiers for constants, use only uppercase letters.
  • In the constant name, words may be separated by underscores.
  • Examples: MAX LENGTH, SUM OF ODD, etc.
  • For class names: Python class names must begin with an uppercase letter.
  • Use camelcase, which requires that each word in an identifier start with a capital letter, to separate words and improve readability.
  • For instance, student name, mobile number, etc.
  • Individual Variables:
  • Underscores are typically used to begin Python built-in types. Except when utilising a private variable, you can avoid this.
  • Instance: _digit
  • named packages:
  • When naming packages, use lowercase.
  • Don't use underscores in your text.
  • Calculus, utilities, etc.
  • Other: Use lowercase letters for naming variables, functions, and modules. In these situations, use underscore as the separator. For instance, emp salary, is complete(), etc. If you'd want, you can also name things using camel casing. The names listed above, for instance, can be expressed as empSalary, isComplete(), etc.
  • The identifier name shouldn't include two underscores at the beginning or end. Only a keyword defined by a language can utilise such naming.
  • It is always a good idea to begin the function name with is for boolean functions. This aids in obtaining a yes/no response. Examples include is paid(), is traveling(), etc. These might be expressed as isTraveling(), isPaid(), etc. if camel case is used.


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