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Keywords
Keywords are predefined and reserved words in Python, which have special meanings and purposes. They cannot be
used as identifiers or variable names. These keywords are part of Python’s syntax and are used to define control flow,
declare functions and classes, handle exceptions, etc.
Following table shows the keywords used in Python:
and as assert async await
break class continue def del
elif else except False finally
for from global if import
in is lambda None nonlocal
not or pass raise return
True try while with yield
Identifiers
Identifiers are the names used to identify variables, functions, classes, modules, and other objects in Python. They act as
labels for these elements, allowing you to refer to them in your code. Identifiers follow certain rules and conventions:
• • Must begin with a letter (a-z, A-Z) or an underscore (_).
• • Subsequent characters can be letters, digits (0-9), or underscores.
• • Case-sensitive (myVar is different from myvar).
• • Cannot be a Python keyword (reserved words).
• • No special characters such as !, @, #, $, %, etc., are allowed within identifiers.
• • Blank spaces within an identifier are disallowed.
For example:
my_variable
calculate_sum
MyClass
Some conventions that can be used while specifying identifiers for more clarity are as follows:
• • Use descriptive names that convey the purpose of the variable, function, etc.
• • Follow the snake_case convention for variable names and function names. This means using all lowercase letters
with words separated by underscores. For example: my_variable, calculate_sum.
• • Follow the PascalCase convention for class names. This means capitalising the first letter of each word, without
underscores. For example: MyClass, BankAccount.
• • Use all uppercase letters with underscores to denote constants. For example: MAX_SIZE, PI.
Literals
Literals in Python represent fixed values that are used directly in the code. They can be of several types:
• • Numeric literals: Represented as integers, floating-point numbers, or complex numbers. Examples: 42, 3.14, 1 + 2j.
• • String literals: Represented as sequences of characters enclosed in single, double, or triple quotes. Examples:
'hello', "world", '''multiline string'''.
• • Boolean literals: Represented as True or False.
• • None literal: Represented as None that indicates the absence of a value.
Operators
In Python, operators can be defined as special symbols which perform arithmetic and logical computation. The values
which the operators use to get the output are called operands.
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