Strings II

More String Methods: case, strip, and startswith

Three more groups of string methods you'll need constantly: case methods (.lower(), .upper(), .title()) for normalizing text, .strip() for trimming whitespace or other characters from the edges, and .startswith() / .endswith() for prefix and suffix checks.

Three more groups of string methods worth knowing: case methods, .strip(), and .startswith() / .endswith().

Let's start with case. .lower() returns a new string with every letter in lowercase:

name = 'Alice SMITH'
print(name.lower())

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Output

.upper() is the opposite. It returns the string in all caps:

greeting = 'hello there'
print(greeting.upper())

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Output

Two more case helpers: .title() capitalizes the first letter of every word, and .capitalize() only capitalizes the very first letter of the string.

text.title()
text.capitalize()

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See the difference on the same input:

book = 'the great gatsby'
print(book.title())
print(book.capitalize())

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Output

What will be the output?

word = 'Python'
print(word.upper())

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Like every string method, these return a new string. The original variable is never changed unless you reassign it.

What will be the output?

name = 'bob'
name.upper()
print(name)

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Next up: .strip(). It removes characters from both ends of a string. By default, it strips whitespace.

Notice the spaces are gone from both sides, but the space in the middle stays:

raw = '   hello world   '
print(raw.strip())

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Output

Pass any string of characters to strip those instead. Here we trim hash signs from both ends:

banner = '###  News  ###'
print(banner.strip('#'))

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Output

If you only want to trim one side, use .lstrip() for the left or .rstrip() for the right.

text.lstrip()
text.rstrip()

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Right-strip removes only the trailing characters:

line = 'data,,,,'
print(line.rstrip(','))

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Output

What will be the output?

s = '...note...'
print(s.strip('.'))

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Finally, two methods that ask a yes-or-no question about a string: .startswith() and .endswith(). Both return a boolean.

Check whether a URL begins with a known prefix:

url = 'https://pychallenger.com'
print(url.startswith('https'))

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Output

Both methods accept a tuple to check several options at once. Handy for file extensions:

name = 'photo.jpg'
print(name.endswith(('.png', '.jpg')))

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Output

What will be the output?

f = 'report.pdf'
print(f.endswith('.txt'))

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What will be the output?

path = 'images/logo.png'
ext = ('.jpg', '.png')
print(path.endswith(ext))

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What will be the output?

raw = '  Hello  '
print(raw.strip().lower())

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