Python Keywords and Identifiers, keywords (reserved words in Python), and identifiers (names given to variables, functions, etc.).
Introduction:
Python keywords are also known as reserved words. Keywords are particular words that act as a key to a code. These are predefined words by Python, so they cannot be used as identifiers.
Identifiers in Python are symbolic names used for identification. They can be a class name, variable name, method name, function name, and more.
Note: Python keywords or reserved words can not be used as an identifier.
Python Keywords:
Python keywords or reserved words are particular words that act as a key to a code. We have “keywords” in every programming language, Python keywords are small letters, and Python is a case-sensitive language.
Keyword | Description |
| and | A logical operator |
| as | To create an alias |
| assert | For debugging |
| break | To break out of a loop |
| class | To define a class |
| continue | To continue to the next iteration of a loop |
| def | To define a function |
| del | To delete an object |
| elif | Used in conditional statements, same as else if |
| else | Used in conditional statements |
| except | Used with exceptions, what to do when an exception occurs |
| False | Boolean value, result of comparison operations |
| finally | Used with exceptions, a block of code that will be executed no matter if there is an exception or not |
| for | To create a for loop |
| from | To import specific parts of a module |
| global | To declare a global variable |
| if | To make a conditional statement |
| import | To import a module |
| in | To check if a value is present in a list, tuple, etc. |
| is | To test if two variables are equal |
| lambda | To create an anonymous function |
| None | Represents a null value |
| nonlocal | To declare a non-local variable |
| not | A logical operator |
| or | A logical operator |
| pass | A null statement, a statement that will do nothing |
| raise | To raise an exception |
| return | To exit a function and return a value |
| True | Boolean value, result of comparison operations |
| try | To make a try…except statement |
| while | To create a while loop |
| with | Used to simplify exception handling |
| yield | To end a function, returns a generator |
Python Identifiers
An identifier is a name given to entities like class, functions, variables, etc. It helps to differentiate one entity from another.
Rules for writing identifiers
1. Identifiers can be a combination of letters in lowercase (a to z) or uppercase (A to Z) or digits (0 to 9) or an underscore _. Names like myClass, var_1 and print_this_to_screen, all are valid example.
2. An identifier cannot start with a digit. 1variable is invalid, but variable1 is a valid name.
3. Keywords cannot be used as identifiers.
global = 1
SyntaxError: invalid syntax
4. We cannot use special symbols like !, @, #, $, % etc. in our identifier.
a@ = 0
SyntaxError: invalid syntax
5. An identifier can be of any length.
