🔹 1. What is a String?

A string is a sequence of characters enclosed in quotes.

Python allows:

• "double quotes"
• 'single quotes'
• '''triple quotes''' (multi-line)

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Example 1: Creating Strings

name = "Sameer"
city = 'Hyderabad'
message = """Welcome to Python"""print(name)
print(city)
print(message)

Output

Sameer
Hyderabad
Welcome to Python

📌 Explanation
Strings store text information such as names, addresses, messages, etc.

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🔹 2. Accessing Characters (Indexing)

Each character in a string has a position (index).

Character	S	a	m	e	e	r
Index	0	1	2	3	4	5

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Example 2: Indexing

name = "Sameer"print(name[0])
print(name[3])
print(name[5])

Output

S
e
r

📌 Explanation

• Index starts from 0
• name[0] means first character

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🔹 3. Negative Indexing

Python also supports negative indexing.

Character	S	a	m	e	e	r
Index	-6	-5	-4	-3	-2	-1

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Example 3

name = "Sameer"print(name[-1])
print(name[-3])

Output

r
e

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🔹 4. String Slicing

Slicing extracts part of a string.

Syntax

string[start : end]

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Example 4

name = "Chandini"print(name[0:4])
print(name[2:6])

Output

Chan
andi

📌 Explanation

• Start index included
• End index excluded

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🔹 5. String Length

len() returns number of characters.

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Example 5

name = "Ayesha"print(len(name))

Output

6

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🔹 6. Convert Case Methods

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Example 6

text = "python programming"print(text.upper())
print(text.lower())
print(text.title())
print(text.capitalize())

Output

PYTHON PROGRAMMING
python programming
Python Programming
Python programming

📌 Explanation

Method	Purpose
upper()	Convert to uppercase
lower()	Convert to lowercase
title()	Capitalize every word
capitalize()	Capitalize first letter

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🔹 7. Removing Spaces

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Example 7

text = "   Sameer   "print(text.strip())

Output

Sameer

📌 Explanation
strip() removes spaces from beginning and end.

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🔹 8. Replacing Text

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Example 8

text = "Hello Sameer"print(text.replace("Sameer", "Ayesha"))

Output

Hello Ayesha

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🔹 9. Checking Text

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Example 9

text = "Python Programming"print("Python" in text)
print("Java" in text)

Output

True
False

📌 Explanation
Checks whether a word exists in the string.

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🔹 10. Splitting Strings

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Example 10

text = "Sameer,Ayesha,Saddam"print(text.split(","))

Output

['Sameer', 'Ayesha', 'Saddam']

📌 Explanation
split() converts string into list

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🔹 11. Joining Strings

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Example 11

names = ["Sameer", "Ayesha", "Gousya"]result = " - ".join(names)print(result)

Output

Sameer - Ayesha - Gousya

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🔹 12. Checking String Type

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Example 12

text = "Python123"print(text.isalpha())
print(text.isdigit())
print(text.isalnum())

Output

False
False
True

📌 Explanation

Method	Meaning
isalpha()	letters only
isdigit()	numbers only
isalnum()	letters + numbers

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🔹 13. String Concatenation

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Example 13

first = "Sameer"
last = "Khan"print(first + " " + last)

Output

Sameer Khan

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🔹 14. String Formatting

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Example 14

name = "Chandini"
age = 22print(f"{name} is {age} years old")

Output

Chandini is 22 years old

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🔹 15. Real-Life Example

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Example 15: Username Check

username = input("Enter username: ")if username.lower() == "sameer":
    print("Access granted")
else:
    print("Access denied")

Sample Output

Enter username: Sameer
Access granted