Python Next Function (With Examples)

This comprehensive guide will explore the intricacies of the next() function, showcasing its syntax, examples, and use cases, to provide you with a deeper understanding of this fundamental Python function.

What is Python next() Function?

Python next() function is used to fetch the next item from the collection. It takes two arguments an iterator and a default value and returns an element.

Python next() Syntax

The syntax of next() function in Python is:

next(iterator, default)

next() Parameters

next() Return Value

• The next() function returns the next item from the iterator.
• If the iterator is exhausted, it returns the default value passed an argument.
• If the default parameter is omitted and the iterator is exhausted. It raises the StopIteration exception.

Here’s the example program of python next() function:

marks = [91, 92, 93, 94, 95]

# convert list to iterator
iterator_marks = iter(marks)

# the next element is the first element
marks_1 = next(iterator_marks)
print(marks_1)

# find the next element which is the second element
marks_2 = next(iterator_marks)
print(marks_2)

When you run the program, this will be the output:

91
92

Also read: Deque Python

Get The next() Item From The Iterator

Here’s another example program on how to get the next() item from the iterator.

list1 = [1, 2, 3, 4, 5]

# converting list to iterator
list_iter = iter(list1)

print("First item in List:", next(list_iter))
print("Second item in List:", next(list_iter))

When you execute the program, this will be the output.

First item in List: 1
Second item in List: 2

Passing Default Value To next()

Here’s another example program of Passing Default Value To next()function.

mylist = iter(["Java", "C++", "PHP"])
x = next(mylist, "Python")
print(x)
x = next(mylist, "Python")
print(x)
x = next(mylist, "Python")
print(x)
x = next(mylist, "Python")
print(x)

When you execute the program, this will be the output:

Java
C++
PHP
Python

Python next() StopIteration

Here’s another example program of python next() stopiteration.

list_iter = iter([1, 2])

print("Next Item:", next(list_iter))
print("Next Item:", next(list_iter))

# this line should raise StopIteration exception
print("Next Item:", next(list_iter))

When you execute the program this will be the output.

Traceback (most recent call last):
StopIteration
Next Item: 1
Next Item: 2

While calling out the range of iterator then it returns the stopiterations error. To avoid this error happens, we will use the default value as an argument.

Applications of the next() Function

The next() function finds its application in various scenarios, enabling efficient and dynamic data processing.

1. File Processing

When reading large files, the next() function helps retrieve lines one by one, optimizing memory usage.

2. Real-time Data Streaming

In real-time data processing, the next() function allows processing data streams as they arrive, without loading the entire data set into memory.

3. Custom Iterators

Developing custom iterators in Python becomes more manageable with the next() function, enabling the iteration of complex data structures.

Conclusion

We completely discussed the different functions of next() in Python, which we learned in this tutorial with the help of examples in a different function. I hope this simple Python Tutorial can help you comply with your requirements regarding Python next() functions.