Python strings are full of handy tools called methods. Because strings are objects, they carry these built-in functions with them.
You can easily change the casing of a string using methods like upper() and lower().
msg = 'Hello World'
print(msg.upper())HELLO WORLD
msg = 'HELLO'
print(msg.lower())hello
Here is the most important rule about strings: Strings are immutable. That means they cannot be changed in place. When you run a method like upper(), it returns a brand new string.
msg = 'hello'
msg.upper()
print(msg)hello
Notice that printing msg still outputs hello in lowercase! If you want to keep the uppercase version, you must assign it to a variable: msg = msg.upper().
The strip() method is perfect for cleaning up messy user input. It removes leading and trailing characters (spaces by default).
msg = ' hello '
print(f'*{msg.strip()}*')*hello*
strip() removes any combination of the specified characters, not just the exact sequence.To swap out parts of a string, use replace(). By default, it replaces all occurrences.
msg = 'I like apples'
print(msg.replace('apples', 'bananas'))I like bananas
The split() method breaks a single string into a list of smaller strings. By default, it splits on whitespace, but you can specify any delimiter.
csv = 'one,two,three'
print(csv.split(','))['one', 'two', 'three']
split() with no arguments correctly handles multiple consecutive spaces as a single separator, unlike split(' ').Do string methods modify the original string in place?
No, strings are immutable. Methods return a new string, leaving the original unchanged. — Strings are immutable in Python. Any method that alters the text actually returns a brand new string.
What does the strip() method remove?
Characters from the very beginning and very end (leading and trailing). — strip() only affects the outside edges (leading and trailing), never the middle.
By default, how many occurrences does replace() swap?
ALL occurrences unless a count argument is provided. — replace() swaps every single match it finds by default.
What happens when you call split() without any arguments?
It splits by any whitespace (spaces, tabs, newlines). — By default, split() targets all whitespace, even if there are multiple spaces in a row.
You are given a messy name string. Convert it to title case and remove the extra spaces at the ends. Print the result.
You can chain methods! Try strip() followed by title().
name = ' jOhn dOe '
print(name.strip().title())Replace all occurrences of 'sad' with 'happy'. Print the result.
Use the replace('old', 'new') method.
mood = 'I am sad. Very sad.'
print(mood.replace('sad', 'happy'))