Python Notes

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Python Syntax

Python syntax ke rules aur structure ko samjhein — indentation, statements, keywords, identifiers aur code likhne ka sahi tarika.

Hindi: Python syntax matlab Python ka grammar — woh rules jinke anusaar aap Python code likhte hain. Jaise Urdu/Hindi mein grammar hoti hai, waise hi Python ka apna ek set of rules hai.

2. Your First Python Program

python example

# Hello World — every programmer's first step!
print("Hello, World!")

Output

Hello, World!

Hindi: print() ek built-in function hai jo screen par kuch bhi dikhata hai. Quotes ke andar jo bhi likhein, woh display hoga.

3. Python Indentation (सबसे ज़रूरी नियम)

Python uses indentation (spaces/tabs at the start of a line) to define code blocks. This is Python's most unique and important rule.

Hindi: Indentation Python ka sabse important rule hai. Doosri languages mein {} curly braces use hote hain blocks ke liye, lekin Python mein spaces/tabs use hote hain.

Comparison with Other Languages

C / Java / JavaScript

if (x > 0) {

print(x); // block defined by {}

}

Python

if x > 0:

print(x) # block defined by indentation

Correct Indentation Example

python example

age = 20

if age >= 18:
    print("Adult")         # 4 spaces indented — inside if block
    print("Can vote!")     # same block
else:
    print("Minor")         # inside else block

print("Program ends")      # outside if-else, no indentation

Output

Adult
Can vote!
Program ends

Wrong Indentation — SyntaxError!

python example

if True:
print("Hello")   # ❌ IndentationError: expected an indented block

Output

IndentationError: expected an indented block after 'if' statement on line 1

ASCII Diagram — Indentation Blocks

Example

if condition: <── block starts with colon statement 1 <── 4 spaces indent (INSIDE block) statement 2 <── same indent = same block if nested: statement 3 <── 8 spaces = nested block statement 4 <── 0 indent = OUTSIDE if block

Hindi: Ek rule yaad rakhein: ek hi block ke andar sabhi statements ka indentation SAME hona chahiye. Standard Python style 4 spaces use karta hai.

4. Python Statements

A statement is a single instruction that Python executes.

Simple Statements

python example

x = 10           # assignment statement
print(x)         # function call statement
x += 5           # augmented assignment
del x            # delete statement

Output

Multi-line Statements (Line Continuation)

Example

# Method 1: Backslash continuation total = 10 + 20 + \ 30 + 40 # Method 2: Inside brackets (preferred) total = (10 + 20 + 30 + 40) print(total) # Multi-line list fruits = [ "apple", "banana", "mango", "orange" ] print(fruits)

Output

100
['apple', 'banana', 'mango', 'orange']

Hindi: Agar statement bahut lamba ho toh backslash \ ya parentheses () use karke agle line mein continue kar sakte hain. Brackets ke andar line continuation automatic hoti hai.

Multiple Statements on One Line (Semicolon)

python example

# Using semicolons — valid but NOT recommended (PEP 8 violation)
x = 5; y = 10; z = 15
print(x, y, z)

Output

5 10 15

Hindi: Semicolon se ek line mein multiple statements likh sakte hain, lekin yeh Python style ke against hai. Avoid karein.

5. Python Keywords (Reserved Words)

Keywords are reserved words that have special meaning in Python. You cannot use them as variable names.

Hindi: Keywords wo special words hain jinhe Python ne apne liye reserve kiya hua hai. Inhe variable names ke roop mein use nahi kar sakte.

python example

import keyword
print(keyword.kwlist)

Output

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await',
 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except',
 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is',
 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return',
 'try', 'while', 'with', 'yield']

Keywords Table

Keyword	Purpose	Example
`if`	Conditional	`if x > 0:`
`else`	Alternative	`else:`
`elif`	Else-if	`elif x == 0:`
`for`	Loop	`for i in range(5):`
`while`	Loop	`while x > 0:`
`def`	Function	`def greet():`
`class`	Class	`class Dog:`
`return`	Return value	`return x`
`import`	Import module	`import math`
`True/False`	Boolean	`x = True`
`None`	Null value	`x = None`
`and/or/not`	Logical ops	`if a and b:`

6. Identifiers (Names)

An identifier is a name given to variables, functions, classes, etc.

Hindi: Identifier matlab naam — jab aap koi variable, function ya class banate hain, toh uska naam identifier hota hai.

Rules for Identifiers

Code example

✅ VALID identifiers:
   name, age, my_variable, _private, MyClass, count1, camelCase

❌ INVALID identifiers:
   1name      (starts with digit)
   my-name    (hyphen not allowed)
   my name    (space not allowed)
   class      (reserved keyword)
   @value     (special char not allowed)

python example

# Valid identifiers
student_name = "Rahul"
_age = 20
MyClass = "Python"
count1 = 100

print(student_name, _age, MyClass, count1)

Output

Rahul 20 Python 100

Python Naming Conventions (PEP 8)

Type	Convention	Example
Variable	`snake_case`	`student_name`
Function	`snake_case`	`get_marks()`
Class	`PascalCase`	`StudentRecord`
Constant	`UPPER_CASE`	`MAX_SIZE = 100`
Private	`_underscore`	`_private_var`
Dunder	`__double__`	`__init__`

7. Case Sensitivity

Python is case-sensitive — Name, name, and NAME are three different identifiers!

Hindi: Python mein capital aur small letters alag hote hain. Name aur name do alag variables hain.

python example

Name = "Rahul"
name = "Priya"
NAME = "AMIT"

print(Name)   # Rahul
print(name)   # Priya
print(NAME)   # AMIT

Output

Rahul
Priya
AMIT

8. Comments in Syntax Context

python example

# This is a single-line comment — Python ignores this

x = 10  # inline comment

"""
This is a multi-line string
often used as a docstring
"""

def greet(name):
    """This function greets a person."""  # docstring
    print(f"Hello, {name}!")

greet("Rahul")

Output

Hello, Rahul!

9. Python Script Structure

A well-structured Python script follows this pattern:

python example

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
Module Docstring: Describe what this script does.
Author: WoHoTech
Date: 2026-06-12
"""

# 1. Standard library imports
import os
import sys

# 2. Third-party imports
# import numpy as np

# 3. Local imports
# from mymodule import myfunction

# 4. Constants
MAX_SIZE = 100
PI = 3.14159

# 5. Functions and Classes
def main():
    """Main function — entry point."""
    print("Python script running!")
    print(f"Python version: {sys.version}")
    print(f"Working directory: {os.getcwd()}")

# 6. Entry point
if __name__ == "__main__":
    main()

Output

Python script running!
Python version: 3.11.x ...
Working directory: C:\Users\...

Hindi: if __name__ == "__main__": block tab run hota hai jab aap script directly chalate hain. Yeh professional Python code ka standard pattern hai.

10. Common Syntax Errors and Fixes

python example

# Error 1: Missing colon
# ❌ Wrong
# if x > 0
#     print(x)

# ✅ Fix
x = 5
if x > 0:
    print(x)

Output

python example

# Error 2: Wrong quotes
# ❌ Wrong
# print("Hello, World!')   # mixed quotes

# ✅ Fix
print("Hello, World!")
print('Hello, World!')    # both work if consistent

Output

Hello, World!
Hello, World!

python example

# Error 3: Missing parentheses in function call
# ❌ Wrong (Python 2 style)
# print "Hello"

# ✅ Fix (Python 3)
print("Hello")

Output

Hello

python example

# Error 4: Undefined variable
# ❌ Wrong
# print(z)    # NameError: name 'z' is not defined

# ✅ Fix — define before use
z = 42
print(z)

Output

11. Interactive Python (REPL)

Example

$ python3 >>> print("Hello") Hello >>> 2 + 3 5 >>> name = "WoHoTech" >>> print(f"Welcome to {name}!") Welcome to WoHoTech! >>> exit()

Hindi: REPL (Read-Eval-Print Loop) ek interactive environment hai jahan aap ek ek line Python code likh kar test kar sakte hain. Terminal mein python3 type karo aur enter karo.

12. PEP 8 — Python Style Guide Quick Reference

Rule	Bad	Good
Indentation	2 spaces / tabs	4 spaces
Line length	>79 chars	≤79 chars
Blank lines	Random	2 between functions
Spaces in expression	`x=10`	`x = 10`
Import style	`import os,sys`	One import per line
Naming	`MyVariable`	`my_variable`

python example

# PEP 8 compliant code example
import os
import sys

MAX_RETRIES = 3


def calculate_area(radius):
    """Calculate circle area."""
    pi = 3.14159
    return pi * radius ** 2


def main():
    area = calculate_area(5)
    print(f"Area = {area:.2f}")


if __name__ == "__main__":
    main()

Output

Area = 78.54

Summary — Python Syntax Rules

┌─────────────────────────────────────────────────────┐ │ PYTHON SYNTAX CHEAT SHEET │ ├─────────────────────────────────────────────────────┤ │ ✅ Use 4 spaces for indentation │ │ ✅ End block header with colon ( : ) │ │ ✅ Case-sensitive identifiers │ │ ✅ No semicolons needed (optional) │ │ ✅ Use # for single-line comments │ │ ✅ Use \ or () for line continuation │ │ ✅ Follow PEP 8 naming conventions │ │ ✅ Keywords cannot be used as identifiers │ └─────────────────────────────────────────────────────┘

Practice Exercises

Exercise 1 — Fix the Syntax Errors

python example

# Fix all errors in this code:
# if True
# print("Hello"
# x=10
#   y = 20
# Print(x + y)

Expected output:

Output

Hello
30

Exercise 2 — Naming Convention

Create variables for:

A student's full name
Their age
Their class section (constant)
A function to print their info

Exercise 3 — Script Structure

Write a complete Python script with:

Proper docstring
At least 2 functions
A main() function
if __name__ == "__main__": block

Interview Questions

Q1. What is the significance of indentation in Python? > Python uses indentation to define code blocks instead of curly braces {}. It is mandatory — incorrect indentation causes IndentationError. Standard is 4 spaces per level.

Q2. Is Python case-sensitive? > Yes, Python is case-sensitive. Variable, variable, and VARIABLE are three distinct identifiers.

Q3. What are Python keywords? Give 5 examples. > Keywords are reserved words with special meaning: if, else, for, while, def, class, return, import, True, False. They cannot be used as variable names.

Q4. What is PEP 8? > PEP 8 is Python's official style guide. It defines conventions for indentation (4 spaces), naming (snake_case for variables, PascalCase for classes), line length (79 chars max), and code organization.

Q5. What is the difference between a syntax error and a runtime error? > A syntax error occurs when the code violates Python's grammar rules and is detected before execution (e.g., missing colon). A runtime error occurs during execution (e.g., dividing by zero, accessing undefined variable).

⚠️ Common Mistakes

1. Indentation Mix — Tabs aur Spaces Mix karna 🚫

python example

# ❌ Wrong — tab aur spaces mix
if True:
    print("Hello")    # spaces
	print("World")    # tab — IndentationError!

Hindi: Kabhi bhi tabs aur spaces mix mat karo. Hamesha 4 spaces use karo. Editor mein "Convert Tabs to Spaces" enable rakhein.

2. Colon ( : ) Bhool Jaana 😅

python example

# ❌ Wrong
if x > 5
    print(x)

# ✅ Correct
if x > 5:
    print(x)

Hindi: if, else, for, while, def, class ke baad colon : lagana zaruri hai. Yeh sabse common beginner mistake hai.

3. `=` aur `==` ka Confusion 🔄

python example

# ❌ Wrong — assignment use kiya comparison ke jagah
if x = 10:    # SyntaxError!
    print("yes")

# ✅ Correct
if x == 10:
    print("yes")

Hindi: = assignment ke liye hai (value dena), == comparison ke liye hai (check karna ki equal hai ya nahi).

4. Keyword ko Variable Name banana 🚷

python example

# ❌ Wrong
class = "10th"    # SyntaxError! 'class' is a keyword
for = 5           # SyntaxError! 'for' is a keyword

# ✅ Correct
student_class = "10th"
loop_count = 5

Hindi: Python ke reserved keywords (jaise class, for, if, return) ko variable name ke roop mein use karna allowed nahi hai.

5. Brackets/Parentheses Band na karna 🔓

Example

# ❌ Wrong print("Hello" # SyntaxError: unexpected EOF fruits = ["apple", "banana" # bracket close nahi kiya # ✅ Correct print("Hello") fruits = ["apple", "banana"]

Hindi: Har opening bracket (, [, { ke liye closing bracket ), ], } hona chahiye. Editor mein bracket matching enable karein.

6. Quotes Mismatch karna 🔀

python example

# ❌ Wrong
message = "Hello, World!'    # single aur double mix
name = 'Rahul"               # mismatch!

# ✅ Correct
message = "Hello, World!"
name = 'Rahul'

Hindi: String start aur end mein same type ke quotes hone chahiye — ya toh dono single ' ' ya dono double " ".

7. `print` mein Parentheses Bhoolna (Python 3) 🖨️

python example

# ❌ Wrong (Python 2 style)
# print "Hello"    # SyntaxError in Python 3!

# ✅ Correct (Python 3)
print("Hello")

Hindi: Python 3 mein print ek function hai, isliye parentheses () zaroori hain. Python 2 style print "text" ab kaam nahi karta.

✅ Key Takeaways

🔹 Indentation is KING — Python mein indentation code blocks define karta hai. Hamesha 4 spaces use karein, tabs se bachein.
🔹 Colon rule — if, else, elif, for, while, def, class ke baad hamesha colon : lagaein.
🔹 Case-sensitive — Python mein Name, name, aur NAME teen alag cheezein hain. Naming mein consistent rahein.
🔹 Keywords are reserved — Python ke 35 keywords (jaise if, for, class, return) ko variable name ke roop mein use nahi kar sakte.
🔹 PEP 8 follow karein — Variables ke liye snake_case, Classes ke liye PascalCase, Constants ke liye UPPER_CASE use karein.
🔹 Line continuation — Long statements ke liye parentheses () ya backslash \ use karein. Parentheses preferred hain.
🔹 Comments likhein — # se single-line comments aur """...""" se docstrings likhein. Code readable banayein.
🔹 REPL for testing — Terminal mein python3 type karke interactive mode mein quick testing karein.
🔹 Script structure — Professional code mein imports → constants → functions → if __name__ == "__main__": pattern follow karein.
🔹 Syntax Error = Grammar Error — Agar Python SyntaxError de, toh samjho code ka grammar galat hai. Colon, brackets, quotes check karein.

❓ FAQ

Q1. Kya Python mein semicolons zaroori hain? > ❌ Nahi! Python mein semicolons optional hain. Aap ek line mein multiple statements likh sakte hain x = 5; y = 10 lekin yeh PEP 8 ke against hai. Recommended: har statement alag line mein likhein.

Q2. Indentation ke liye Tabs use karein ya Spaces? > Hamesha 4 spaces use karein. Python officially spaces recommend karta hai (PEP 8). Tabs aur spaces mix karna TabError deta hai. Apne editor mein "Insert Spaces" option enable karein.

Q3. Python mein kitne keywords hain? > Python 3.11+ mein 35 keywords hain. import keyword; print(len(keyword.kwlist)) se check kar sakte hain. Yeh list Python version ke saath thoda change ho sakti hai.

Q4. Kya variable name mein Hindi/Unicode characters use kar sakte hain? > Technically haan — Python 3 Unicode identifiers support karta hai (नाम = "Rahul" valid hai). Lekin professional code mein English names hi use karein for readability aur team collaboration.

Q5. SyntaxError: invalid syntax ka kya matlab hai? > Iska matlab hai ki Python aapke code ko samajh nahi paa raha. Common reasons: colon : missing, bracket band nahi kiya, quotes mismatch, ya keyword galat use kiya. Error message mein line number dekhein aur us line ke aas-paas check karein.

Q6. Kya Python mein blank lines matter karti hain? > Code execution mein blank lines se koi fark nahi padta — Python unhe ignore karta hai. Lekin readability ke liye PEP 8 kehta hai: functions ke beech 2 blank lines, class methods ke beech 1 blank line rakhein.

Q7. Python mein maximum line length kitni honi chahiye? > PEP 8 ke according 79 characters per line recommended hai. Comments ke liye 72 characters. Agar line lamba ho toh parentheses () ya backslash \ se break karein. Modern projects mein kuch teams 100-120 chars bhi allow karti hain.

Q8. if __name__ == "__main__": ka kya role hai? > Yeh line check karti hai ki script directly run ho rahi hai ya import ho rahi hai. Agar directly run ho (python script.py) toh __name__ ki value "__main__" hoti hai aur block execute hota hai. Import hone par yeh block skip ho jaata hai. Yeh professional Python code ka standard pattern hai.

Exam Focus

Revise definitions, diagrams, examples, and short-answer points for Python Syntax.

Interview Use

Prepare one clear explanation, one practical example, and one common mistake for this Python Master Course topic.

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BasicsPython CommentsHow to write comments in Python — single-line, multi-line, docstrings, and best practices to make code readable and maintainable.BasicsPython Data TypesPython ke sabhi built-in data types — int, float, str, bool, list, tuple, set, dict, None — ko deeply samjhein examples, diagrams aur comparisons ke saath.BasicsPython Input and OutputPython mein user se input lena aur output dikhana — input(), print(), f-strings, formatting, file I/O basics aur real-world input handling ke saath complete guide.BasicsPython OperatorsPython ke sabhi operators — arithmetic, comparison, logical, bitwise, assignment, identity, membership, aur walrus — examples aur precedence table ke saath complete guide.BasicsPython Strings BasicsPython strings ko deeply samjhein — creation, indexing, slicing, built-in methods, formatting, escape sequences aur real-world string manipulation ke saath complete beginners guide.BasicsPython Type CastingPython mein ek data type se doosre mein convert karna — int(), float(), str(), bool(), list(), tuple(), set(), dict() — implicit aur explicit casting ke saath complete guide.

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Python Notes

Python Syntax

Python syntax ke rules aur structure ko samjhein — indentation, statements, keywords, identifiers aur code likhne ka sahi tarika.

Hindi: Python syntax matlab Python ka grammar — woh rules jinke anusaar aap Python code likhte hain. Jaise Urdu/Hindi mein grammar hoti hai, waise hi Python ka apna ek set of rules hai.

2. Your First Python Program

python example

# Hello World — every programmer's first step!
print("Hello, World!")

Output

Hello, World!

Hindi: print() ek built-in function hai jo screen par kuch bhi dikhata hai. Quotes ke andar jo bhi likhein, woh display hoga.

3. Python Indentation (सबसे ज़रूरी नियम)

Python uses indentation (spaces/tabs at the start of a line) to define code blocks. This is Python's most unique and important rule.

Hindi: Indentation Python ka sabse important rule hai. Doosri languages mein {} curly braces use hote hain blocks ke liye, lekin Python mein spaces/tabs use hote hain.

Comparison with Other Languages

C / Java / JavaScript

if (x > 0) {

print(x); // block defined by {}

}

Python

if x > 0:

print(x) # block defined by indentation

Correct Indentation Example

python example

age = 20

if age >= 18:
    print("Adult")         # 4 spaces indented — inside if block
    print("Can vote!")     # same block
else:
    print("Minor")         # inside else block

print("Program ends")      # outside if-else, no indentation

Output

Adult
Can vote!
Program ends

Wrong Indentation — SyntaxError!

python example

if True:
print("Hello")   # ❌ IndentationError: expected an indented block

Output

IndentationError: expected an indented block after 'if' statement on line 1

ASCII Diagram — Indentation Blocks

Example

Hindi: Ek rule yaad rakhein: ek hi block ke andar sabhi statements ka indentation SAME hona chahiye. Standard Python style 4 spaces use karta hai.

4. Python Statements

A statement is a single instruction that Python executes.

Simple Statements

python example

x = 10           # assignment statement
print(x)         # function call statement
x += 5           # augmented assignment
del x            # delete statement

Output

Multi-line Statements (Line Continuation)

Example

Output

100
['apple', 'banana', 'mango', 'orange']

Hindi: Agar statement bahut lamba ho toh backslash \ ya parentheses () use karke agle line mein continue kar sakte hain. Brackets ke andar line continuation automatic hoti hai.

Multiple Statements on One Line (Semicolon)

python example

# Using semicolons — valid but NOT recommended (PEP 8 violation)
x = 5; y = 10; z = 15
print(x, y, z)

Output

5 10 15

Hindi: Semicolon se ek line mein multiple statements likh sakte hain, lekin yeh Python style ke against hai. Avoid karein.

5. Python Keywords (Reserved Words)

Keywords are reserved words that have special meaning in Python. You cannot use them as variable names.

Hindi: Keywords wo special words hain jinhe Python ne apne liye reserve kiya hua hai. Inhe variable names ke roop mein use nahi kar sakte.

python example

import keyword
print(keyword.kwlist)

Output

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await',
 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except',
 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is',
 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return',
 'try', 'while', 'with', 'yield']

Keywords Table

Keyword	Purpose	Example
`if`	Conditional	`if x > 0:`
`else`	Alternative	`else:`
`elif`	Else-if	`elif x == 0:`
`for`	Loop	`for i in range(5):`
`while`	Loop	`while x > 0:`
`def`	Function	`def greet():`
`class`	Class	`class Dog:`
`return`	Return value	`return x`
`import`	Import module	`import math`
`True/False`	Boolean	`x = True`
`None`	Null value	`x = None`
`and/or/not`	Logical ops	`if a and b:`

6. Identifiers (Names)

An identifier is a name given to variables, functions, classes, etc.

Hindi: Identifier matlab naam — jab aap koi variable, function ya class banate hain, toh uska naam identifier hota hai.

Rules for Identifiers

Code example

✅ VALID identifiers:
   name, age, my_variable, _private, MyClass, count1, camelCase

❌ INVALID identifiers:
   1name      (starts with digit)
   my-name    (hyphen not allowed)
   my name    (space not allowed)
   class      (reserved keyword)
   @value     (special char not allowed)

python example

# Valid identifiers
student_name = "Rahul"
_age = 20
MyClass = "Python"
count1 = 100

print(student_name, _age, MyClass, count1)

Output

Rahul 20 Python 100

Python Naming Conventions (PEP 8)

Type	Convention	Example
Variable	`snake_case`	`student_name`
Function	`snake_case`	`get_marks()`
Class	`PascalCase`	`StudentRecord`
Constant	`UPPER_CASE`	`MAX_SIZE = 100`
Private	`_underscore`	`_private_var`
Dunder	`__double__`	`__init__`

7. Case Sensitivity

Python is case-sensitive — Name, name, and NAME are three different identifiers!

Hindi: Python mein capital aur small letters alag hote hain. Name aur name do alag variables hain.

python example

Name = "Rahul"
name = "Priya"
NAME = "AMIT"

print(Name)   # Rahul
print(name)   # Priya
print(NAME)   # AMIT

Output

Rahul
Priya
AMIT

8. Comments in Syntax Context

python example

# This is a single-line comment — Python ignores this

x = 10  # inline comment

"""
This is a multi-line string
often used as a docstring
"""

def greet(name):
    """This function greets a person."""  # docstring
    print(f"Hello, {name}!")

greet("Rahul")

Output

Hello, Rahul!

9. Python Script Structure

A well-structured Python script follows this pattern:

python example

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
Module Docstring: Describe what this script does.
Author: WoHoTech
Date: 2026-06-12
"""

# 1. Standard library imports
import os
import sys

# 2. Third-party imports
# import numpy as np

# 3. Local imports
# from mymodule import myfunction

# 4. Constants
MAX_SIZE = 100
PI = 3.14159

# 5. Functions and Classes
def main():
    """Main function — entry point."""
    print("Python script running!")
    print(f"Python version: {sys.version}")
    print(f"Working directory: {os.getcwd()}")

# 6. Entry point
if __name__ == "__main__":
    main()

Output

Python script running!
Python version: 3.11.x ...
Working directory: C:\Users\...

Hindi: if __name__ == "__main__": block tab run hota hai jab aap script directly chalate hain. Yeh professional Python code ka standard pattern hai.

10. Common Syntax Errors and Fixes

python example

# Error 1: Missing colon
# ❌ Wrong
# if x > 0
#     print(x)

# ✅ Fix
x = 5
if x > 0:
    print(x)

Output

python example

# Error 2: Wrong quotes
# ❌ Wrong
# print("Hello, World!')   # mixed quotes

# ✅ Fix
print("Hello, World!")
print('Hello, World!')    # both work if consistent

Output

Hello, World!
Hello, World!

python example

# Error 3: Missing parentheses in function call
# ❌ Wrong (Python 2 style)
# print "Hello"

# ✅ Fix (Python 3)
print("Hello")

Output

Hello

python example

# Error 4: Undefined variable
# ❌ Wrong
# print(z)    # NameError: name 'z' is not defined

# ✅ Fix — define before use
z = 42
print(z)

Output

11. Interactive Python (REPL)

Example

$ python3 >>> print("Hello") Hello >>> 2 + 3 5 >>> name = "WoHoTech" >>> print(f"Welcome to {name}!") Welcome to WoHoTech! >>> exit()

Hindi: REPL (Read-Eval-Print Loop) ek interactive environment hai jahan aap ek ek line Python code likh kar test kar sakte hain. Terminal mein python3 type karo aur enter karo.

12. PEP 8 — Python Style Guide Quick Reference

Rule	Bad	Good
Indentation	2 spaces / tabs	4 spaces
Line length	>79 chars	≤79 chars
Blank lines	Random	2 between functions
Spaces in expression	`x=10`	`x = 10`
Import style	`import os,sys`	One import per line
Naming	`MyVariable`	`my_variable`

python example

# PEP 8 compliant code example
import os
import sys

MAX_RETRIES = 3


def calculate_area(radius):
    """Calculate circle area."""
    pi = 3.14159
    return pi * radius ** 2


def main():
    area = calculate_area(5)
    print(f"Area = {area:.2f}")


if __name__ == "__main__":
    main()

Output

Area = 78.54

Summary — Python Syntax Rules

Practice Exercises

Exercise 1 — Fix the Syntax Errors

python example

# Fix all errors in this code:
# if True
# print("Hello"
# x=10
#   y = 20
# Print(x + y)

Expected output:

Output

Hello
30

Exercise 2 — Naming Convention

Create variables for:

A student's full name
Their age
Their class section (constant)
A function to print their info

Exercise 3 — Script Structure

Write a complete Python script with:

Proper docstring
At least 2 functions
A main() function
if __name__ == "__main__": block

Interview Questions

Q2. Is Python case-sensitive? > Yes, Python is case-sensitive. Variable, variable, and VARIABLE are three distinct identifiers.

⚠️ Common Mistakes

1. Indentation Mix — Tabs aur Spaces Mix karna 🚫

python example

# ❌ Wrong — tab aur spaces mix
if True:
    print("Hello")    # spaces
	print("World")    # tab — IndentationError!

Hindi: Kabhi bhi tabs aur spaces mix mat karo. Hamesha 4 spaces use karo. Editor mein "Convert Tabs to Spaces" enable rakhein.

2. Colon ( : ) Bhool Jaana 😅

python example

# ❌ Wrong
if x > 5
    print(x)

# ✅ Correct
if x > 5:
    print(x)

Hindi: if, else, for, while, def, class ke baad colon : lagana zaruri hai. Yeh sabse common beginner mistake hai.

3. `=` aur `==` ka Confusion 🔄

python example

# ❌ Wrong — assignment use kiya comparison ke jagah
if x = 10:    # SyntaxError!
    print("yes")

# ✅ Correct
if x == 10:
    print("yes")

Hindi: = assignment ke liye hai (value dena), == comparison ke liye hai (check karna ki equal hai ya nahi).

4. Keyword ko Variable Name banana 🚷

python example

# ❌ Wrong
class = "10th"    # SyntaxError! 'class' is a keyword
for = 5           # SyntaxError! 'for' is a keyword

# ✅ Correct
student_class = "10th"
loop_count = 5

Hindi: Python ke reserved keywords (jaise class, for, if, return) ko variable name ke roop mein use karna allowed nahi hai.

5. Brackets/Parentheses Band na karna 🔓

Example

# ❌ Wrong print("Hello" # SyntaxError: unexpected EOF fruits = ["apple", "banana" # bracket close nahi kiya # ✅ Correct print("Hello") fruits = ["apple", "banana"]

Hindi: Har opening bracket (, [, { ke liye closing bracket ), ], } hona chahiye. Editor mein bracket matching enable karein.

6. Quotes Mismatch karna 🔀

python example

# ❌ Wrong
message = "Hello, World!'    # single aur double mix
name = 'Rahul"               # mismatch!

# ✅ Correct
message = "Hello, World!"
name = 'Rahul'

Hindi: String start aur end mein same type ke quotes hone chahiye — ya toh dono single ' ' ya dono double " ".

7. `print` mein Parentheses Bhoolna (Python 3) 🖨️

python example

# ❌ Wrong (Python 2 style)
# print "Hello"    # SyntaxError in Python 3!

# ✅ Correct (Python 3)
print("Hello")

Hindi: Python 3 mein print ek function hai, isliye parentheses () zaroori hain. Python 2 style print "text" ab kaam nahi karta.

✅ Key Takeaways

🔹 Indentation is KING — Python mein indentation code blocks define karta hai. Hamesha 4 spaces use karein, tabs se bachein.
🔹 Colon rule — if, else, elif, for, while, def, class ke baad hamesha colon : lagaein.
🔹 Case-sensitive — Python mein Name, name, aur NAME teen alag cheezein hain. Naming mein consistent rahein.
🔹 Keywords are reserved — Python ke 35 keywords (jaise if, for, class, return) ko variable name ke roop mein use nahi kar sakte.
🔹 PEP 8 follow karein — Variables ke liye snake_case, Classes ke liye PascalCase, Constants ke liye UPPER_CASE use karein.
🔹 Line continuation — Long statements ke liye parentheses () ya backslash \ use karein. Parentheses preferred hain.
🔹 Comments likhein — # se single-line comments aur """...""" se docstrings likhein. Code readable banayein.
🔹 REPL for testing — Terminal mein python3 type karke interactive mode mein quick testing karein.
🔹 Script structure — Professional code mein imports → constants → functions → if __name__ == "__main__": pattern follow karein.
🔹 Syntax Error = Grammar Error — Agar Python SyntaxError de, toh samjho code ka grammar galat hai. Colon, brackets, quotes check karein.

❓ FAQ

Exam Focus

Revise definitions, diagrams, examples, and short-answer points for Python Syntax.

Interview Use

Prepare one clear explanation, one practical example, and one common mistake for this Python Master Course topic.

Search Terms

python-master-course, python master course, python, master, course, basics, syntax, python syntax

Continue learning this concept

PreviousPython Operators NextPython Strings Basics

2. Your First Python Program

3. Python Indentation (सबसे ज़रूरी नियम)

Comparison with Other Languages

C / Java / JavaScript

Python

Correct Indentation Example

Wrong Indentation — SyntaxError!

ASCII Diagram — Indentation Blocks

4. Python Statements

Simple Statements

Multi-line Statements (Line Continuation)

Multiple Statements on One Line (Semicolon)

5. Python Keywords (Reserved Words)

Keywords Table

6. Identifiers (Names)

Rules for Identifiers

Python Naming Conventions (PEP 8)

7. Case Sensitivity

8. Comments in Syntax Context

9. Python Script Structure

10. Common Syntax Errors and Fixes

11. Interactive Python (REPL)

12. PEP 8 — Python Style Guide Quick Reference

Summary — Python Syntax Rules

Practice Exercises

Exercise 1 — Fix the Syntax Errors

Exercise 2 — Naming Convention

Exercise 3 — Script Structure

Interview Questions

⚠️ Common Mistakes

1. Indentation Mix — Tabs aur Spaces Mix karna 🚫

2. Colon ( : ) Bhool Jaana 😅

3. = aur == ka Confusion 🔄

4. Keyword ko Variable Name banana 🚷

5. Brackets/Parentheses Band na karna 🔓

6. Quotes Mismatch karna 🔀

7. print mein Parentheses Bhoolna (Python 3) 🖨️

✅ Key Takeaways

❓ FAQ

Continue learning this concept

2. Your First Python Program

3. Python Indentation (सबसे ज़रूरी नियम)

Comparison with Other Languages

C / Java / JavaScript

Python

Correct Indentation Example

Wrong Indentation — SyntaxError!

ASCII Diagram — Indentation Blocks

4. Python Statements

Simple Statements

Multi-line Statements (Line Continuation)

Multiple Statements on One Line (Semicolon)

5. Python Keywords (Reserved Words)

Keywords Table

6. Identifiers (Names)

Rules for Identifiers

Python Naming Conventions (PEP 8)

7. Case Sensitivity

8. Comments in Syntax Context

9. Python Script Structure

10. Common Syntax Errors and Fixes

11. Interactive Python (REPL)

12. PEP 8 — Python Style Guide Quick Reference

Summary — Python Syntax Rules

Practice Exercises

Exercise 1 — Fix the Syntax Errors

Exercise 2 — Naming Convention

Exercise 3 — Script Structure

Interview Questions

⚠️ Common Mistakes

1. Indentation Mix — Tabs aur Spaces Mix karna 🚫

2. Colon ( : ) Bhool Jaana 😅

3. = aur == ka Confusion 🔄

4. Keyword ko Variable Name banana 🚷

5. Brackets/Parentheses Band na karna 🔓

6. Quotes Mismatch karna 🔀

7. print mein Parentheses Bhoolna (Python 3) 🖨️

✅ Key Takeaways

❓ FAQ

Continue learning this concept

3. `=` aur `==` ka Confusion 🔄

7. `print` mein Parentheses Bhoolna (Python 3) 🖨️

3. `=` aur `==` ka Confusion 🔄

7. `print` mein Parentheses Bhoolna (Python 3) 🖨️