Python Keywords & Identifiers
Python Keywords
Keywords are the reserved words in python .
We cannot use a keyword as a variable name, function name or any other identifier. They are used to define the syntax and structure of the Python language.
In Python, keywords are case sensitive.
There are various keywords in Python .
All the keywords except True
, False
and None
are in lowercase and they must be written as it is. The list of all the keywords is given below.
#Get all keywords
import keyword
print(keyword.kwlist)
and the out put will be
['and', 'as', 'assert', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'exec', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'not', 'or', 'pass', 'print', 'raise', 'return', 'try', 'while', 'with', 'yield']
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
- 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 likemyClass
,var_1
andprint_this_to_screen
, all are valid example. - An identifier cannot start with a digit.
1variable
is invalid, butvariable1
is perfectly fine. - Keywords cannot be used as identifiers..
>>> global = 1
File "<interactive input>", line 1
global = 1
^
SyntaxError: invalid syntax
We cannot use special symbols like !, @, #, $, % etc. in our identifier.
>>> a@ = 0
File "<interactive input>", line 1
a@ = 0
^
SyntaxError: invalid syntax
Things to Remember
Python is a case-sensitive language. This means, Variable
and variable
are not the same. Always name identifiers that make sense.
While, c = 10
is valid. Writing count = 10
would make more sense and it would be easier to figure out what it does even when you look at your code after a long gap.
Multiple words can be separated using an underscore, this_is_a_long_variable
.