Lesson 06

split() and join()

Learn how to break a string into a list with split() and rebuild it into a string using join() through visual diagrams and real-world examples.

Beginner25 min

What you'll learn

Topic	Focus
`split()`	Convert String → List
Custom delimiters	`-`, `#`, `$`, `/`
Date parsing	Extract day, month & year
`join()`	Convert List → String

Visual roadmap

These two methods are opposites.

String → split() → List → join() → String

Golden rule: split() breaks · join() builds

1. split() → Default (spaces)

By default, split() separates words using whitespace.

python

s = "Python is an oop lang"

words = s.split()

print(words)
# ['Python', 'is', 'an', 'oop', 'lang']

print(len(words))
# 5

2. split(delimiter)

Provide a delimiter to split on a specific character.

08-07-2023 split by dash into day month year

python

dob = "08-07-2023"

parts = dob.split("-")

print(parts)
# ['08', '07', '2023']

print(parts[0])  # Day
print(parts[1])  # Month
print(parts[2])  # Year

3. Different delimiters

You can split using any separator.

python

s = "Apple#Banana#Kiwi"

print(s.split("#"))
# ['Apple', 'Banana', 'Kiwi']

s = "Apple/Banana/Kiwi"

print(s.split("/"))
# ['Apple', 'Banana', 'Kiwi']

4. Trailing delimiter

A separator at the end creates an empty last item.

123$456$678$ — trailing $ yields empty string

python

s = "123$456$678$"

print(s.split("$"))
# ['123', '456', '678', '']

Warning: The last '' represents nothing after the final delimiter.

5. Nested splitting

Sometimes data contains multiple separators.

Apple#Mango-Kiwi#Guava — split # then split -

python

s = "Apple#Mango-Kiwi#Guava"

x = s.split("#")
print(x)

y = x[1].split("-")
print(y)

Output:

text

['Apple', 'Mango-Kiwi', 'Guava']
['Mango', 'Kiwi']

6. join() → Build a string

join() combines list or tuple items into one string.

List chips joined with space into sentence

python

lst = ["Python", "is", "an", "oop", "lang"]

sentence = " ".join(lst)

print(sentence)
# Python is an oop lang

Memory: join() = glue between list items

7. Different separators with join()

The string before .join() becomes the separator.

python

cities = ["HYD", "BANG", "AP"]

print("".join(cities))
# HYDBANGAP

print(" ".join(cities))
# HYD BANG AP

Comma separated:

python

print(",".join(cities))
# HYD,BANG,AP

8. join() works with tuples

Any iterable works — not just lists.

python

t = ("Rossum", "is", "Father", "of", "Python")

print(" ".join(t))
# Rossum is Father of Python

9. split() ↔ join() relationship

These methods are exact opposites.

Direction	Method	Returns
String → Parts	`split()`	List
Parts → String	`join()`	String

Playground example

python

s = "Python is an oop lang"

words = s.split()

print(words, len(words))

dob = "08-07-2023"

parts = dob.split("-")

print("Day=", parts[0])
print("Month=", parts[1])
print("Year=", parts[2])

lst = ["Python", "is", "an", "oop", "lang"]

sentence = " ".join(lst)

print(sentence)

Expected output:

text

['Python', 'is', 'an', 'oop', 'lang'] 5

Day= 08
Month= 07
Year= 2023

Python is an oop lang

Use the lesson playground at the bottom of the page to run this code live.

Quick knowledge check

What is the default delimiter for split()?
Answer: Whitespace (spaces, tabs, newlines)
What does "06-05-2024".split("-") return?
Answer: ['06', '05', '2024']
How do you join ['a', 'b', 'c'] with commas?
Answer:

python

",".join(["a", "b", "c"])
# a,b,c

30-second visual revision

String Text hub — split, join, delimiter

Method	Easy memory
`split()`	Break a string into pieces
`split("-")`	Parse dates
`join()`	Glue list items together
`" ".join()`	Build readable sentences

Interview shortcut: Split = String → List · Join = List → String · The string before join() is the separator.

Next: startswith() and endswith().

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← lstrip(), rstrip(), and strip()

startswith() and endswith() →