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FLWhat is a String in Python?
ā¢ A string is a sequence of characters.
ā¢ Written inside single quotes, double quotes, or triple quotes.
Examples:
"Python"
'Hello World'
"""This is a string"""
How Python Stores Strings (Important Concept)
Internally, Python stores a string as:
ā¢ A sequence (array) of characters
ā¢ Each character has an index
Example:
"PYTHON"
Index 0 1 2 3 4 5
Char P Y T H O N
So you can access characters using indexing:
ā¢ First character ā index 0
ā¢ Last character ā index -1
Why Strings are Immutable in Python (Very Important)
š Meaning of Immutable
Immutable means:
Once a string is created, it cannot be changed.
What You CANNOT Do
name = "Python"
name [0] = "J" # ā Error
Python does not allow this.
ā
What Actually Happens
name = "Python"
name = "Jython"
ā¢ Old string "Python" is not modified
ā¢ A new string "Jython" is created
ā¢ Variable name now points to the new string
4ļøā£ String Operations (Core Concepts)
ā Concatenation (Joining)
"Hello" + "World" # HelloWorld
š Repetition
"Hi" * 3 # HiHiHi
š Membership
"a" in "apple" # True
š Length
len("Python") # 6
Important String Functions (Must Know)
5 š¤ Case Conversion Functions
upper() ā Convert to uppercase
text = "python"
text.upper()
ā
Output: "PYTHON"
š§ Use case: Display usernames in CAPS, headings
lower() ā Convert to lowercase
email = "NAGA@GMAIL.COM"
email.lower()
ā
Output: "naga@gmail.com"
š§ Use case: Email comparison (emails are case-insensitive)
6 title() ā First letter of every word capital
name = "naga balla"
name.title()
ā
Output: "Naga Balla"
š§ Use case: Names, headings
capitalize() ā Only first character capital
msg = "hello world"
msg.capitalize()
ā
Output: "Hello world"
š§ Use case: Sentence formatting
swapcase() ā Upper ā Lower
text = "PyThOn"
text.swapcase()
ā
Output: "pYtHoN"
š§ Use case: Text transformations, fun effects
āļø Trimming Functions (Very Common)
strip() ā Remove spaces (both sides)
name = " Naga "
name.strip()
ā
Output: "Naga"
š§ Use case: User input cleaning
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