Chapter Review Questions

1. What is printed by this fragment? Predict first, then run the cell to check:

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   >>> s = "question"
   >>> print(len(s))
   8
   >>> print(s[2])
   e
   >>> print(s[2:5])
   est
   >>> print(s[3:])
   stion
   >>> print(s.find("ti"))
   4
   >>> print(s.find("to"))
   -1
   

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2. What is printed by this fragment? Predict first, then run the cell to check:

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   >>> s = "Word"
   >>> s.upper()
   'WORD'
   >>> print(s)
   Word
   

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3. What is printed by this fragment? Predict first, then run the cell to check:

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   >>> a = "hi"
   >>> b = a.upper()
   >>> print(a + b)
   hiHI
   

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4. Strings and mutability.

   1. Are strings mutable or immutable?

   2. What does that mean in practice when you call a method like s.upper()?

5. Both s.find(sub) and s.index(sub) search for a substring. What is the difference in their behavior when the substring is not present in s?

6. Write an expression that extracts the last three characters of a string s, without using a literal index number.

7. What does s[::-1] do?

8. Write a function count_vowels(s) that returns the number of vowel characters (a, e, i, o, u, case-insensitive) in string s.

9. What is printed by this fragment? Predict first, then run the cell to check:

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   >>> parts = "2024-05-01".split("-")
   >>> print(parts)
   ['2024', '05', '01']
   >>> print("-".join(parts))
   2024-05-01
   

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10. Write a function title_case(s) that returns s converted to title case (first letter of each word capitalized) without using the built-in str.title() method. Use split() and join().