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The join() Function in Python

Python supports object-oriented programming and has a concise, readable, and easy-to-learn syntax. It is no wonder that it is one of the most popular programming languages. An integral part of Python are its built-in functions. 

We've written a series of articles to help you learn and brush up on the most useful Python functions. In this article, we’ll learn about Python's join() function and how to use it. 

If you are preparing for a tech interview, check out our technical interview checklist, interview questions page, and salary negotiation e-book to get interview-ready! Also, read Python String join() Method, Python Exit commands, and Type and Isinstance In Python for more content on Python coding interview preparation.

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In this article, we’ll cover:

  • What Is the join() Function in Python and What Does It Do?
  • The join() Function in Python: Syntax
  • The join() Function in Python: Example
  • FAQs on the join() Function in Python

What Is the join() Function in Python and What Does It Do?

The join() function in Python is a built-in string method. It joins all elements in an iterable with a given string separator into one string. It returns a string with all the elements joined with the desired separator. Please note that the desired separator can only be of the type string. Also, the elements inside the iterable need to be strings.

The join() Function in Python: Syntax



Iterables are objects that can return their members one at a time, like sequences and dictionaries. 

Python’s join() function takes an iterable like a list, tuple, dictionary, string, set, etc., as a parameter. 

Return Value: 

In Python, join() returns a string. The string returned contains all the elements of an iterable concatenated with the desired string separator. Please note that if the iterable contains any non-string elements, the TypeError exception will be raised.

The join() Function in Python: Example

Here, we take a look at how you can use the Python string method join() the next time you need it:


# Using join() in Python 3 
listExample = ["do","re","mi","fa","so","la","ti"] 

# Joining elements of listExample by "-" 
joinBy = "-"
joinedString = joinBy.join(listExample)

# Using join() function to join elements with empty/no separator.


['do', 're', 'mi', 'fa', 'so', 'la', 'ti']

Found this article helpful? You can learn about more Python functions on the learn page. 

FAQs on the join() Function in Python

Q1. What does join() do in Python?

The join() function in Python is a string method that returns a string in which a specific string separator joins all the elements of an iterable. 

Q2. Can you join a list in Python?

Yes. You can join any iterable containing string elements in Python using join(). Since a list is an iterable, you can join its elements using join().

Q3. How do you join words in Python?

You can use the string method separatorString.join(iterable) to join a list of strings connected by the separator separatorString, which could be an empty string, whitespace, newline character, etc.

Q4. How do you join numbers in Python?

You can convert each integer to a string and store it in an iterable like a list, then use the join() function using your desired separator like comma, space, empty string, etc., based on your need.

Q5. What is split and join in Python?

By default, the split() function breaks a string into a list of words. The join() function joins all elements in an iterable into one string using your desired glue, called the string separator.

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