How to sum strings in Python

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Borislav Hadzhiev

Last updated: Jul 4, 2022

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Sum strings in Python #

To sum strings in Python:

  1. Call the str.join() method on an empty string.
  2. Pass the iterable (e.g. a list of strings) to the join() method.
  3. The result will be a string containing the items of the iterable.
main.py
my_list = ['a', 'b', 'c'] # ✅ sum list of strings # 👇️ without a separator my_str = ''.join(my_list) print(my_str) # 👉️ 'abc' # 👇️ with a space separator my_str_2 = ' '.join(my_list) print(my_str_2) # 👉️ 'a b c' # 👇️ with comma separator my_str_3 = ', '.join(my_list) print(my_str_3) # 👉️ 'a, b, c'

The str.join method takes an iterable as an argument and returns a string which is the concatenation of the strings in the iterable.

Note that the method raises a TypeError if there are any non-string values in the iterable.

If your list contains numbers, or other types, convert all of the values to string before calling join().

main.py
my_list = ['a', 1, 'b', 2, 'c', 3] my_str = ''.join(map(str, my_list)) print(my_str) # 👉️ 'a1b2c3'

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

We used the function to convert each item in the list to a string, before passing the items to the str.join() method.

The string the join() method is called on is used as the separator between elements.

main.py
my_list = ['a', 'b', 'c'] my_str = '-'.join(my_list) print(my_str) # 👉️ 'a-b-c'

If you need to join the list of strings with spaces, call the method on a string that contains a space.

main.py
my_list = ['a', 'b', 'c'] # 👇️ with a space separator my_str = ' '.join(my_list) print(my_str) # 👉️ 'a b c'

If you don't need a separator and just want to join the iterable's elements into a string, call the join() method on an empty string.

main.py
my_list = ['a', 'b', 'c'] my_str = ''.join(my_list) print(my_str) # 👉️ 'abc'
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