How is the string.join(str_list, ''") implemented under the hood in Python?

Question

I know that concatenating two strings using the += operator makes a new copy of the old string and then concatenates the new string to that, resulting in quadratic time complexity.

This answer gives a nice time comparison between the += operation and string.join(str_list, ''). It looks like the join() method runs in linear time (correct me if I am wrong). Out of curiosity, I wanted to know how the string.join(str_list, '') method is implemented in Python since strings are immutable objects?

str.join(iterable), so join method takes any Iterable object not only list of strings — Rustam-Z, Nov 13 '22 at 12:50

score 1 · Answer 1 · answered Oct 27 '18 at 19:44

1

It's implemented in C, so python mutability is less important. You can find the appropriate source here: unicodeobject.c

answered Oct 27 '18 at 19:44

CJR

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How is the string.join(str_list, ''") implemented under the hood in Python?

1 Answers1