Python Syntax And Token

Part 1: What is python syntax?

Syntax is the rule that define how the code is to be written and execution.

Part 1.1: Key Rules

Python is case-sensitive language that means name ≠ Name.

Python use Indentation (Spaces) instant of braces {} unlike other programming language to define Blocks.

Statements usually Ends with newline, No semicolon required unlike other language.

Because of those python code is easy to read, write and understand to the human.
This feature will allow to easily modify the code according to need of the programmer.

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Part 2: What is Token in Python??

A token in Python is the smallest individual unit of a program that has meaning to the Python interpreter. Tokens are the basic Building Block of code.They are Five types of the Tokens in Python programming language.

Part 2.1: Keywords

• Keywords are case-sensitive.
• Keywords are reserved words that have predefine fixed meaning.
• Keywords are reserved, that’s why we cannot use those words in name of variable, class, Function, or any other identifier.
• There is no import requirement of any libraries. Their always available in python environment.

They’re not formally divided into“Official Types,” but we can group them by how they’re used in the language.

Group Name	Types
Control Flow Keywords	if, elif, else, for, while, break, continue, pass
Function & Class Definition Keywords	def, class, return, yield, lambd
Logical & Boolean Keywords	and, or, not, True, False, None
Import & Module Keywords	import, from, as
Membership & Identity Keyword	in, not in,is, is not
Variable Scope Keywords	static, this, public, private, protected, var
Loop & Exception Control Keywords	break, continue, pass, finally
Exception Handling Keywords	try, except, finally, raise, assert
Miscellaneous Keywords	del,with,yield

Part 2.2: Identifiers

It is a name that define by programmer to identify the variable, class, function or any other objects. It is case-sensitive so, Variable or variable or variable there all are different identifiers.

Part 2.2.1: They are some rule for identifiers

• It is combination of Uppercase, lowercase, digits, and underscore.
   NAME   ✔️vaild
   name    ✔️vaild
   name1    ✔️vaild
   first_name  ✔️vaild
   _name    ✔️vaild
   _NamE1   ✔️vaild


• It cannot be start with number or digit.
   1name  ❌ Invaild
   name1  ✔️vaild


• It can be start with character or underscore.
   name    ✔️vaild
   _name   ✔️vaild
   1_name  ❌ Invaild
  


• It cannot be use any reserved keyword.
   string  ❌ Invaild
   def   ❌ Invaild
   and   ❌ Invaild
   if    ❌ Invaild
   not    ❌ Invaild
  


• It cannot use any special character.
   @Name  ❌ Invaild
   &First  ❌ Invaild
   First%  ❌ Invaild
  

Part 2.2.2: Where to use Identifier in programming

1. Variable Name
Example :user_name = "Aman"
      total_score = 95
      is_logged_in = True


2. Function Name
when we create
    def greet():
    print("Hello, world!")

When we call
    greet()


3. Class Name
When we create
     class StudentProfile:
     def __init__(self, name, age):
     self.name = name
     self.age = age


4. Module Name
When we create
    File Name math_utils.py

When we call in pyhton:
     import math_utils
     result = math_utils.calculate_total(100, 18)

Part 2.2.3: Valid v/s Invaild Identifier

Valid	Invalid
name	1name
First_name	First-name
Student1	Student 1
className	class

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Part 2.3: Literals

A literal is a raw value assigned to a variable or used directly in an expression. Those values can not be change during the execution
For Example :
  Statment A: X=10  Explantion :X is assign by 10
  Statment B: print(10)  Explantion :Here result print directly value 10
  Statment C: X=10
  print(X+2) Explantion :X is assign by 10 and addition by directly value 2.

Part 2.3.1 Types of Literals

1. Numeric literals

Integers	10, -5, 0, -10	X = 10
Floats	3.14, -0.001	X = 3.14
Complex	2 + 3j	X = 2 + 3j



2. String literals

Single Quotes	'hello'	message = 'Hello World'
Double quotes	"world"	name = "Alice"
Triple quotes	'''text''' or """text"""	"""This is a multi-line string"""



3. Boolean literals

True		is_active = True
False		is_closed = False



4. Collection literals

List	[1, 2, 3]	numbers = [1, 2, 3, 4]
Tuple	(1, 2, 3)	coordinates = (10, 20)
Dictionary	{"a": 1, "b": 2}	person = {"name": "Aman", "age": 20}

5. Special literal
  None (represents absence of value)

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Part 2.4: Operators

An operator is a symbol that performs an operation on values (operands).

Types of operators in Python

1. Arithmetic operators

   Addition	+
   Subtraction	-
   Multiplication	*
   Division	/
   Floor Division	//
   Modulus	%
   Exponentiation	**



2. Relational or Comparison Operators

   Equal To	"=="
   Not equal To	"!="
   Less Than	"<"
   Greater than	">"
   Less than or Equal To	"<="
   Greater than or Equal To	">="



3. Logical Operators

   AND	and
   OR	or
   NOT	not



4. Assignment operators

   Assign the value	=
   Addition and assign	+=
   Subtraction and assign	-=
   Multiplication and assign	*=
   Division and assign	/=
   Floor division and assign	//=
   Modulus and assign	%=
   Exponentiation and Assign	**=

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Part 2.5: Delimiters

• They don’t perform calculations like operators.
• They define the boundaries of a statement.
• They define the structure like starting and ending blocks.
• They separate elements like item in list.
• To make a code readable and organized delimiters are used.

Name	Meaning	Example
Parentheses ( )	Is used for grouping expressions, function calls(commonly used)	Statement A : print("Hello") Statement B : x = (2 + 3) * 5
Square Brackets [ ]	Is used for lists and indexing(commonly used)	Statement A : numbers = [1, 2, 3, 4] print(numbers[0])
Curly Braces { }	Is used for dictionaries and sets(commonly used)	Statement A : student = {"name": "Rahul", "age": 20} Statement B : unique_numbers = {1, 2, 3}
Comma ,	Is used to separate values(commonly used)	Statement A : a, b, c = 1, 2, 3 print(a, b, c)
Colon :	Is used to start a block of code(loops, functions, conditions)(commonly used)	Statement A : if True:   print("Hello")
Dot .	Is used to access methods or properties(commonly used)	Statement A : name = "python" print(name.upper())
Equal =	Is used for assignment(commonly used)	Statement A : x = 10
Semicolon ;	Is used to write multiple statements in one line(not commonly used)	Statement A : a = 5; b = 10; print(a + b)
At Symbol @	Is used for decorators (not commonly used)	Statement A : def my_decorator(func):   return func @my_decorator def greet():   print("Hello")

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Part 3 : Quick Summary

We call keyword as a “vocabulary” of a python programming language.

Identifiers = names of variables, functions, classes, etc.

Identifier Cannot be Python keywords.

Identifier Should be meaningful and Readable.

Operator is a Symbols to perform operation

Delimiters define boundaries and structure of a program.