LEARN COMPLETE PYTHON IN 24 HOURS

9. Strings (Deep Dive)

Strings are sequences of characters (text). They are immutable (cannot be changed after creation, like tuples).

9.1 String Slicing & Negative Indexing

Strings support indexing and slicing — just like lists.

Indexing:

• Positive: starts from 0 (left to right)

• Negative: starts from -1 (right to left)

Example:

Python

text = "Python Programming" print(text[0]) # P print(text[6]) # P (space is also a character) print(text[-1]) # g print(text[-9]) # r

Slicing Syntax:

Python

text[start:end:step] # start → inclusive # end → exclusive # step → optional (default 1)

Examples:

Python

print(text[0:6]) # Python print(text[7:]) # Programming print(text[:6]) # Python print(text[::2]) # Pto rgamn (every 2nd character) print(text[::-1]) # gnimmargorP nohtyP (reversed string!) print(text[-12:-6]) # Progra (negative slicing) print(text[7:18:3]) # Porm (start 7, step 3)

Tip: Slicing creates a new string — original remains unchanged. Common use: Reverse a string → text[::-1]

9.2 String Methods (upper, lower, strip, replace, split, join, find, etc.)

Strings have many useful built-in methods.

MethodDescriptionExampleResultupper()Convert to uppercase"hello".upper()"HELLO"lower()Convert to lowercase"HELLO".lower()"hello"title()Capitalize first letter of each word"python is fun".title()"Python Is Fun"capitalize()Capitalize first letter only"python is fun".capitalize()"Python is fun"strip()Remove leading/trailing whitespace" hello ".strip()"hello"lstrip() / rstrip()Remove left/right whitespace only" hello ".lstrip()"hello "replace(old, new)Replace substring"I like Java".replace("Java", "Python")"I like Python"split()Split string into list (default: space)"apple banana mango".split()['apple', 'banana', 'mango']split(sep)Split by specific separator"name,age,city".split(",")['name', 'age', 'city']join()Join list elements with separator"-".join(["2026", "03", "05"])"2026-03-05"find(sub)Return first index of substring (or -1)"hello world".find("world")6index(sub)Like find(), but raises error if not found"hello".index("l")2startswith() / endswith()Check prefix/suffix"python.py".endswith(".py")Truecount(sub)Count occurrences"banana".count("a")3

Practical Examples:

Python

sentence = " Python is awesome! Learn Python today. " print(sentence.strip()) # "Python is awesome! Learn Python today." print(sentence.upper()) # " PYTHON IS AWESOME! LEARN PYTHON TODAY. " print(sentence.replace("Python", "Java")) # " Java is awesome! Learn Java today. " words = sentence.split() # ['Python', 'is', 'awesome!', 'Learn', 'Python', 'today.'] print(words) date_parts = ["2026", "March", "05"] print("/".join(date_parts)) # 2026/March/05 print(sentence.find("awesome")) # 10 (first occurrence) print(sentence.count("Python")) # 2

Tip: join() is the opposite of split() — very useful for creating CSV, paths, etc.

9.3 Check if String Contains Something

Several ways to check:

1. in operator (most common & readable)

Python

text = "I love Python programming" print("Python" in text) # True print("java" in text) # False print("python" in text.lower()) # True (case-insensitive)

2. find() or index()

Python

if text.find("love") != -1: print("Found 'love' at position:", text.find("love")) # 2

3. startswith() / endswith()

Python

filename = "report.pdf" print(filename.endswith(".pdf")) # True print(filename.startswith("report")) # True

Tip: For case-insensitive check → convert both to lower/upper first.

9.4 Escape Characters

Use \ (backslash) to include special characters inside strings.

Escape SequenceMeaningExampleOutput\nNew line"Line1\nLine2"Line1 Line2\tTab"Name:\tAnshuman"Name: Anshuman\\Backslash"Path\to\file"Path\to\file\"Double quote inside """He said "Hello""He said "Hello"\'Single quote inside '''It's Python'It's Python

Example:

Python

print("Hello\nWorld!") # Hello # World! print("C:\\Users\\Anshuman") # C:\Users\Anshuman print("She said, \"I love Python!\"") # She said, "I love Python!"

Tip: Use raw strings to ignore escapes → add r before quotes:

Python

print(r"C:\new\test") # C:\new\test (no new line)

9.5 Multiline Strings

Create strings that span multiple lines.

Two ways:

1. Triple quotes """ """ or ''' '''

Python

message = """ Hello Anshuman, Welcome to Python tutorial 2026! This is a multiline string. Enjoy learning! """ print(message)

Output:

text

Hello Anshuman, Welcome to Python tutorial 2026! This is a multiline string. Enjoy learning!

2. Using \ at end of each line (inside single/double quotes)

Python

long_text = "Python is great because " \ "it is easy to read " \ "and write." print(long_text)

Tip: Triple quotes preserve newlines and indentation — very useful for:

• Docstrings (function/class documentation)

• HTML templates

• SQL queries

• Long messages/emails

Mini Project – Text Cleaner & Analyzer

Python

text = input("Enter some text: ").strip() # Clean and analyze clean_text = text.lower().replace(",", "").replace(".", "") words = clean_text.split() print("Original:", text) print("Lowercase:", text.lower()) print("Word count:", len(words)) print("Contains 'python'?", "python" in clean_text) print("First word:", words[0] if words else "Empty")

This completes the full Strings (Deep Dive) section — now you can handle text like a pro!

Dictionaries. Dictionaries are one of Python's most powerful and commonly used data structures — perfect for storing data in key-value pairs (like a real dictionary: word → meaning).

Written in simple English with syntax, many practical examples, outputs, and tips — ready to copy-paste directly into your webpage.

📚 Amazon Book Library

All my books are FREE on Amazon Kindle Unlimited🌍 Exclusive Country-Wise Amazon Book Library – Only Here!

On GlobalCodeMaster.com you’ll find complete, ready-to-use lists of my books with direct Amazon links for every country.

Belong to India, Australia, USA, UK, Canada or any other country? Just click your country’s link and enjoy:

✅ Any eBook FREE on Kindle Unlimited ✅ Or buy at incredibly low prices

400+ fresh books written in 2025-2026 with today’s latest AI, Python, Machine Learning & tech trends – nowhere else will you find this complete country-wise collection on one platform!

Choose your country below and start reading instantly 🚀

BOOK LIBRARY USA 2026 LINK

BOOK LIBRARY INDIA 2026 LINK

BOOK LIBRARY AUSTRALIA 2026 LINK

BOOK LIBRARY CANADA 2026 LINK

BOOK LIBRARY UNITED KINGDOM 2026 LINK

BOOK LIBRARY GERMANY 2026 LINK

BOOK LIBRARY FRANCE 2026 LINK

BOOK LIBRARY ITALY 2026 LINK

BOOK LIBRARY SPAIN 2026 LINK

BOOK LIBRARY NETHERLANDS 2026 LINK

BOOK LIBRARY BRAZIL 2026 LINK

BOOK LIBRARY MEXICO 2026 LINK

BOOK LIBRARY JAPAN 2026 LINK

BOOK LIBRARY POLAND 2026 LINK

BOOK LIBRARY IRELAND 2026 LINK

BOOK LIBRARY SWEDEN 2026 LINK

BOOK LIBRARY BELGIUM 2026 LINK