String Manipulation

Working with text - formatting, methods, and string operations.

String Basics

Strings are sequences of characters.
Use single or double quotes.
Triple quotes for multi-line strings.
Strings are immutable.

# Creating strings
name = 'Alice'
message = "Hello, World!"
multi = '''This is
a multi-line
string'''

# Concatenation
greeting = "Hello" + " " + "World"
print(greeting)  # Hello World

# Repetition
laugh = "ha" * 3
print(laugh)  # hahaha

String Formatting

f-strings (Python 3.6+): Most readable and efficient.
format() method: Older but still useful.
% operator: Legacy formatting.

name = "Alice"
age = 25

# f-strings (recommended)
msg = f"My name is {name} and I'm {age} years old"
print(msg)

# format() method
msg = "My name is {} and I'm {} years old".format(name, age)
print(msg)

# With expressions
x = 10
y = 20
print(f"Sum: {x + y}")  # Sum: 30

String Methods

upper(), lower(): Change case
strip(): Remove whitespace
split(): Split into list
replace(): Replace substring
find(): Find substring position

text = "  Hello, World!  "

print(text.upper())           # "  HELLO, WORLD!  "
print(text.lower())           # "  hello, world!  "
print(text.strip())           # "Hello, World!"
print(text.replace("World", "Python"))  # "  Hello, Python!  "

# Split and join
words = "apple,banana,cherry".split(",")
print(words)  # ['apple', 'banana', 'cherry']

joined = " ".join(words)
print(joined)  # "apple banana cherry"

String Slicing

Access parts of strings using [start:end].
Negative indices count from the end.
Step parameter for skipping characters.

text = "Python Programming"

print(text[0:6])    # "Python"
print(text[7:])     # "Programming"
print(text[:6])     # "Python"
print(text[-11:])   # "Programming"

# Every other character
print(text[::2])    # "Pto rgamn"

# Reverse string
print(text[::-1])   # "gnimmargorP nohtyP"

String Checking

startswith(), endswith(): Check prefix/suffix
isdigit(), isalpha(): Check character types
in operator: Check if substring exists

text = "Python3"

print(text.startswith("Py"))   # True
print(text.endswith("on"))     # False
print(text.isdigit())          # False
print("123".isdigit())         # True
print(text.isalpha())          # False

# Membership
print("Py" in text)            # True
print("Java" in text)          # False