Strings, Working with Text

Master text manipulation, the most common thing programs do

A string is any sequence of characters, letters, numbers, symbols, spaces. Most real programs deal heavily with text: names, messages, URLs, files.

Key string operationspython

text = "Hello, World!"

print(len(text))           # Length: 13
print(text.upper())        # HELLO, WORLD!
print(text.lower())        # hello, world!
print(text.replace("World", "Python"))  # Hello, Python!
print(text[0])             # H  (first character)
print(text[-1])            # !  (last character)
print(text[0:5])           # Hello  (slice)

String indexing starts at 0. The first character is at position 0, the second at 1, etc. text[0:5] means "characters from position 0 up to (not including) 5".

Checking and splitting stringspython

email = "alice@example.com"

print("@" in email)          # True, checks if @ is in the string
print(email.startswith("alice"))  # True
print(email.endswith(".com"))     # True
print(email.split("@"))      # ['alice', 'example.com']
print(email.strip())         # removes whitespace from both ends

🌍In the Real World...

Log files are strings. URLs are strings. YAML configs are strings. 90% of DevOps automation is string manipulation, parsing log lines, building API URLs, formatting config values.

Practice Exercises

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Exercise 1 of 3easy

⏱ 00:00

Reverse a String

Write a function reverse_string(s) that returns the string reversed.
Example: reverse_string("hello") → "olleh"

solution.py

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Exercise 2 of 3easy

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Count Vowels

Write a function count_vowels(s) that returns the number of vowels (a, e, i, o, u) in the string. Case-insensitive.

solution.py

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Exercise 3 of 3medium

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Is a Palindrome?

Write a function is_palindrome(s) that returns True if the string reads the same forwards and backwards, ignoring case and spaces.
Examples: "racecar" → True, "hello" → False, "A man a plan a canal Panama" → True

solution.py

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