Day 3: Python Programming

Operators
Operators are symbols used to perform operations on variables and values.

1. Arithmetic Operators Used for mathematical calculations. Operator Meaning Example
2. Addition 10 + 5
3. Subtraction 10 - 5

4. Multiplication 4 * 3
   / Division 10 / 2
   % Modulus (Remainder) 10 % 3 → 1
   ** Exponent (Power) 2 ** 3 → 8
   // Floor Division 10 // 3 → 3
   Example:
   a = 10
   b = 3
   print(a + b)
   print(a % b)
   print(a // b)

5. Comparison Operators
   Used to compare values — returns True/False
   Operator Meaning
   == Equal to
   != Not equal to

   Greater than
   < Less than
   = Greater or equal
   <= Less or equal
   print(5 > 3)
   print(10 == 20)

6. Logical Operators
   Operator Meaning Example
   and both conditions true a > 5 and a < 20
   or any one true a > 5 or a < 2
   not reverse value not True = False
   x = 10
   print(x > 5 and x < 15)
   print(x > 5 or x > 100)
   print(not(x > 5))

7. Assignment Operators
   Operator Meaning
   = Assign value
   += a = a + 5
   -= a = a – 5
   = a = a × 5
   /= a = a ÷ 5
   **Example:*
   x = 10
   x += 5 # x = 15
   x *= 2 # x = 30

String
1. What is a String?
A string is text inside quotes.
name = "Aruna"

2. String Indexing
Each character has a position (index).
A r u n a
0 1 2 3 4
name = "Aruna"
print(name[0]) # A
print(name[3]) # n

3. String Slicing
Extract part of string.
word = "Python"
print(word[0:3]) # Pyt
print(word[2:6]) # thon
print(word[:4]) # Pyth
print(word[2:]) # thon

4. Important String Functions
upper() – converts to uppercase
name = "aruna"
print(name.upper()) # ARUNA
lower()
print("HELLO".lower())
title()
print("welcome to python".title())
replace()
text = "I love python"
print(text.replace("love", "like"))
len() – length of string
print(len("Python"))

5. Loop Through String
for ch in "hello":
print(ch)

6. Check Substring
text = "I love Python"
print("Python" in text) # True
print("java" in text) # False

7. Count Vowels Program
word = "education"
count = 0
for ch in word:
if ch in "aeiou":
count += 1
print("Vowels =", count)