next()

The next() function returns the next element from an iterator object.

next(iterator_object, [default_parameter])

The iterator_object is required. The default_parameter is optional and is printed if the end of the iterator is reached.

Note: If the next element is missing from the object, the default_parameter is returned. Without a set default_parameter, a StopIteration error is thrown.

In this example, a list called list_items is converted to an iterable object via the iter() function, and each element is printed by means of the next() function:

list_items = iter(["Hi", 27, "Python", 10])
print(next(list_items))
print(next(list_items))
print(next(list_items))
print(next(list_items))

This outputs the following:

Hi
27
Python
10

If one more print() runs without the default parameter, an StopIteration error will be thrown:

Traceback (most recent call last):
  File "main.py", line 6, in <module>
    print(next(list_items))
StopIteration

Note: This can also be done with a for loop. However, the for loop actually generates its own iterator object and applies the next() function between each element. Since there is no risk of overflowing the list, a default parameter is not needed:

list_items = iter(["Hi", 27, "Python", 10])
for item in list_items:
  print(item)

This example iterates over the same list with the next() function, but prevents the program from crashing with a default parameter:

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