Case conversion

text = "Hello World"

print(text.upper())  # "HELLO WORLD"
print(text.lower())  # "hello world"
print(text.title())  # "Hello World"
print(text.capitalize())  # "Hello world"

Checking content

text = "Hello123"

print(text.isalpha())  # False (has numbers)
print(text.isdigit())  # False (has letters)
print(text.isalnum())  # True (letters and numbers)
print(text.startswith("Hello"))  # True
print(text.endswith("123"))  # True

Splitting and joining

# Split into list:
text = "apple,banana,cherry"
fruits = text.split(",")  # ['apple', 'banana', 'cherry']

# Join list into string:
fruits = ['apple', 'banana', 'cherry']
text = ",".join(fruits)  # "apple,banana,cherry"

Stripping whitespace

text = "  hello world  "

print(text.strip())  # "hello world" (both sides)
print(text.lstrip())  # "hello world  " (left only)
print(text.rstrip())  # "  hello world" (right only)

Finding and replacing

text = "Hello World"

# Find position:
print(text.find("World"))  # 6
print(text.find("Python"))  # -1 (not found)

# Replace:
new_text = text.replace("World", "Python")
print(new_text)  # "Hello Python"

Formatting

name = "Alice"
age = 30

# f-strings (Python 3.6+):
message = f"My name is {name} and I'm {age}"

# .format():
message = "My name is {} and I'm {}".format(name, age)