8.5 String Conversion

str()

Converts virtually any object into its human-readable string representation — used constantly for logging, printing, and building messages.

>>> str(42)
'42'

Converting Numbers to Strings

>>> str(42), str(3.14), str(True)
('42', '3.14', 'True')

Converting Collections to Strings

str() on a list/dict/tuple produces a debug-friendly text representation matching how it would be typed as a literal — useful for logging, but not the format to show an end user (for that, format the contents explicitly).

>>> str([1, 2, 3])
'[1, 2, 3]'
>>> str({"a": 1})
"{'a': 1}"

Quick Interview Answer

“str() converts virtually any object into its human-readable string form — for numbers that’s the obvious text representation, and for a collection it produces the same text you’d type to construct it as a literal (str([1, 2, 3]) is '[1, 2, 3]'). That collection representation is meant for debugging and logging, not end-user display — showing a raw str(some_dict) to a user is a common shortcut that reads poorly; format the contents deliberately instead.”

Common Mistakes

• Using str(some_list) or str(some_dict) directly in user-facing output instead of formatting the contents explicitly — technically works, but reads like debug output.
• Forgetting str(True) is 'True' (capitalized), not 'true' — a frequent source of bugs when building JSON-like text manually instead of using the json module.