Day 4 – String Manipulation in Python

Strings are sequences of characters, enclosed in single or double quotes. Mastering string manipulation is crucial for coding interviews.

🧵 1. Creating Strings

• str1 = "Hello"
• str2 = 'World'
• Multi-line: """This is multiline string"""

📏 2. String Indexing & Slicing

• Indexing: str[0] for first character
• Negative indexing: str[-1] for last character
• Slicing: str[1:4] gives characters from index 1 to 3

🔁 3. Common String Operations

• len(s): Length of the string
• s.upper(), s.lower(), s.title(), s.capitalize()
• s.strip(): Removes whitespaces
• s.replace("a", "b"): Replace characters
• s.find("word"), s.index("word")
• "Python" in s: Check if substring exists

🧩 4. String Concatenation & Formatting

• Using +: "Hello" + " World"
• Using f-strings: f"Hello {name}"
• Using format(): "{} is {}".format("Python", "awesome")

🔢 5. String Conversion

• str(123): Convert int to string
• int("123"): Convert string to int
• float("3.14")

🔍 6. String Methods (Interview Focus)

• split(): Split into list of words
• join(): Combine list into string
• startswith(), endswith()
• isdigit(), isalpha(), isalnum()
• count(sub): Count occurrences

🎯 7. String Immutability

Strings are immutable in Python. Operations return a new string instead of modifying the original.

❓ 8. Common Interview Questions

• Reverse a string
• Check for palindrome
• Find duplicate characters
• Count vowels and consonants
• Remove punctuation from a string

🧠 9. Example: Reverse a String

📘 10. Resources

• Official Python String Methods
• W3Schools - Python Strings

🔁 Practice daily to master these concepts!