Chapter I Python Revision Tour – I

📘 Python Revision Tour – I

🔹 1.1 Introduction

• Python is a high-level, interpreted programming language
• Developed by Guido van Rossum
• Used in:
• Web development
• Data science
• AI/ML
• Automation

✅ Key Features:

• Easy syntax
• Platform independent
• Open-source
• Object-oriented

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🔹 1.2 Tokens in Python

👉 Smallest unit of a program

Types:

• Keywords
• Identifiers
• Literals
• Operators
• Punctuators

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🔹 1.2.1 Keywords

• Reserved words (cannot be used as names)

import keyword
print(keyword.kwlist)

Examples: if, else, True, False, None

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🔹 1.2.2 Identifiers (Names)

Rules:

• Start with letter or _
• Cannot start with digit
• No spaces
• Case-sensitive

✔ Valid: total_marks
❌ Invalid: 2marks

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🔹 1.2.3 Literals (Values)

• Fixed values

Type	Example
Integer	10
Float	3.14
String	"Hello"
Boolean	True

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🔹 1.2.4 Operators

Types:

• Arithmetic → + - * / // % **
• Relational → == != > <
• Logical → and or not
• Assignment → = += -=

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🔹 1.2.5 Punctuators

Symbols used in Python:
( ) [ ] { } , : . ; ' "

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🔹 1.3 Barebones of a Python Program

print("Hello World")

👉 No need for:

·        main()

·        Semicolon

·        Compilation

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🔹 1.4 Variables and Assignments

x = 10
name = "Bhav"

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🔸 1.4.1 Dynamic Typing

    No need to declare type

x = 10
x = "Hello"

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🔸 1.4.2 Multiple Assignments

a = b = c = 10
x, y = 5, 10

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🔹 1.5 Simple Input and Output

name = input("Enter name: ")
print("Hello", name)

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🔹 1.6 Data Types

• int
• float
• str
• bool

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🔹 1.7 Mutable and Immutable Types

Type	Nature
List	Mutable
String	Immutable
Tuple	Immutable

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🔹 1.8 Expressions

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🔸 1.8.1 Arithmetic Evaluation

print(10 + 5 * 2)  # 20

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🔸 1.8.2 Relational Expressions

print(10 > 5)  # True

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🔸 1.8.3 Logical Expressions

print(True and False)

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🔸 1.8.4 Type Casting

int("10")
float(5)
str(100)

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🔸 1.8.5 Math Library Functions

import math
math.sqrt(16)
math.pow(2,3)

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🔹 1.9 Statement Flow Control

• Controls execution order

Types:

·        Sequential

·        Selection

·        Iteration

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🔹 1.10 The if Conditionals

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🔸 1.10.1 Plain if

if x > 0:
    print("Positive")

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🔸 1.10.2 if-else

if x % 2 == 0:
    print("Even")
else:
    print("Odd")

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🔸 1.10.3 if-elif

if marks >= 90:
    print("A")
elif marks >= 75:
    print("B")
else:
    print("C")

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🔸 1.10.4 Nested if

if x > 0:
    if x < 10:
        print("Single digit")

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🔸 1.10.5 Storing Conditions

cond = (x > 5)
if cond:
    print("True")

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🔹 1.11 Looping Statements

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🔸 1.11.1 for Loop

for i in range(1,6):
    print(i)

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🔸 1.11.2 while Loop

i = 1
while i <= 5:
    print(i)
    i += 1

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🔹 1.12 Jump Statements

for i in range(5):
    if i == 3:
        break

• break → exits loop
• continue → skips iteration

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🔹 1.13 More on Loops

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🔸 1.13.1 Loop else

for i in range(3):
    print(i)
else:
    print("Done")

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🔸 1.13.2 Nested Loops

for i in range(3):
    for j in range(2):
        print(i, j)

🧠 Viva + Important Questions

    What are tokens?