all Python 3Strings (str)function

str.join

union

Concatenate an iterable of strings using the string as the separator.

Syntax

sep.join(iterable)

The separator is the string you call the method on: it is ','.join(items), never items.join(','), and that inversion trips up most beginners. join does no conversion — an iterable of ints raises TypeError, so wrap it in map(str, ...) first. Building a string with += in a loop rebuilds it on every step, while join walks the sequence and allocates the result once.

Examples

print(','.join(['a', 'b', 'c']))  # → a,b,c
print(''.join(['1', '2', '3']))   # → 123
print('-'.join('abc'))            # → a-b-c

See also

Common errors

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