How to return multiple values from a function in Python

Posted: 2019-09-18 / Tags: Python

Returning multiple values from a function is quite cumbersome in C and other languages, but it is very easy to do with Python.

See the following post for the definition of functions by def.

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Return multiple values using commas

In Python, you can return multiple values by simply return them separated by commas.

As an example, define a function that returns a string and a number as follows: Just write each value after the return, separated by commas.

def test():
    return 'abc', 100

In Python, comma-separated values are considered tuples without parentheses, except where required by syntax. For this reason, the function in the above example returns a tuple with each value as an element.

Note that it is actually the comma which makes a tuple, not the parentheses. The parentheses are optional, except in the empty tuple case, or when they are needed to avoid syntactic ambiguity.
Built-in Types - Tuples — Python 3.7.4 documentation

The return value is tuple.

result = test()

# ('abc', 100)
# <class 'tuple'>

Each element has a type defined in the function.

# abc
# <class 'str'>

# 100
# <class 'int'>

Of course, specifying an index that exceeds the number of defined return values will occur an error.

# print(result[2])
# IndexError: tuple index out of range

You can unpack and assign multiple return values to different variables.

a, b = test()

# abc

# 100

Same for 3 or more return values.

def test2():
    return 'abc', 100, [0, 1, 2]

a, b, c = test2()

# abc

# 100

# [0, 1, 2]

Return list

Using [] returns list instead of tuple.

def test_list():
    return ['abc', 100]

result = test_list()

# ['abc', 100]
# <class 'list'>
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