Working with Strings

Read, combine, search, clean, and loop through text with strings.

12 min read 10 quiz questions

Strings are text

A string is a sequence of characters inside quotes. You can index and slice it just like a list.

Strings are immutable, so methods return new strings instead of changing the original one.

Example 1: index, slice, and combine text

word = 'Python'
print(word[0])
print(word[-1])
print(word[1:4])
print(word + ' 3')
print('ha' * 3)

The first character is at index 0. + joins strings, and * repeats a string.

Clean and split text

Example 2: useful string methods

message = '  Hello, Python  '
clean = message.strip()
words = clean.lower().split(', ')
print(clean.upper())
print(words)
print(' - '.join(words))
print(clean.replace('Python', 'world'))

strip() removes surrounding whitespace. split() makes a list, while join() turns a sequence of strings into one string.

Find and write special characters

Example 3: raw strings, escapes, and searching

path = r'C:\new\notes'
text = 'first line\nsecond line'
print(path)
print(text)
print('banana'.find('na'))
print('Python'.startswith('Py'))

\n is an escape sequence for a new line. A raw string begins with r, so backslashes are kept as ordinary characters. find() returns the first position or -1; startswith() returns True or False.

Example 4: count and loop through characters

name = 'Ada'
print(len(name))
for letter in name:
    print(letter)

Key points

Strings are ordered, immutable characters.
You can index and slice a string.
Methods such as upper() return new strings.
split() makes a list and join() combines strings.
Use len() and a for loop to work through text.

Worked example

A courier app cleans a typed name and builds a tracking slug from an ID.

Example

raw_name = "  md. rahim  "
clean = raw_name.strip().title()
slug = "BD-4821".lower().replace("-", "")
print(clean, slug)

How it works, step by step

.strip() removes surrounding spaces.
.title() capitalises each word.
Chaining methods applies them left to right in one expression.

References & Further Reading

Related entries from PyLabs's own reference library.

split() (Split text into a list of pieces.)
strip() (Remove whitespace or chosen characters from both ends.)
replace() (Replace matching text with new text.)

Your notes

Practice exercise

Not passed yet

Set text = ' red,blue '. Remove surrounding spaces, split on the comma, then join the colors with ' | ' and print the result.

Expected output: red | blue

# Write your code below

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Working with Strings quiz

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