coding-mentor-agent/kb/python-course-kb-practical-python/wiki/exercises/1-13-extracting-individual-characters-and-substrings.md

id, source_exercise_id, title, section, source_path, source_repo, source_commit, student_visible_solution, has_private_solution, skip

id	source_exercise_id	title	section	source_path	source_repo	source_commit	student_visible_solution	has_private_solution	skip
practical-python-1.13	1.13	Extracting individual characters and substrings	1.4 Strings	01_Introduction/04_Strings.md	https://github.com/dabeaz-course/practical-python	93dca856b41c61a0a0f85ae334116e4c125629ea	false	false	false

Exercise 1.13: Extracting individual characters and substrings

Source: Practical Python Programming, 01_Introduction/04_Strings.md.

Exercise 1.13: Extracting individual characters and substrings

Strings are arrays of characters. Try extracting a few characters:

>>> symbols[0]
?
>>> symbols[1]
?
>>> symbols[2]
?
>>> symbols[-1]        # Last character
?
>>> symbols[-2]        # Negative indices are from end of string
?
>>>

In Python, strings are read-only.

Verify this by trying to change the first character of symbols to a lower-case 'a'.

>>> symbols[0] = 'a'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' object does not support item assignment
>>>

关联来源

• summaries/04_Strings