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Python List Size

In Python, lists contain several kinds of data, including strings and integers.

Commas separate all the items; a list is indicated by enclosing the values in square brackets.

We can use the built-in Python len() method in Python to determine a list's length.

To calculate the length of the given list, in addition to using the len() method, we may also implement a for loop and the length_hint() method.

In this tutorial, we will demonstrate three distinct methods for determining a list's length for you.

How to Use a Python for Loop to Determine a List's Length?

Since a list is iterable, like a string and dictionary, we may use Python's usual for loop to determine its length.

The naive technique is the name given to this approach.

We can see how to use this Python's naive approach to get the given list's length in the example below.

Code

# Python program to show how to use a for loop to find the length of a list

List = ["Python", "List", "Length", "Tutorial", 35, True, 93]

# Initializing a counter variable to count the items in the list
counter = 0

# Starting a for loop
for item in List:
    # Incrementing the counter variable by one at every iteration. Thus counting items
    counter = counter + 1

# Printing the length of the list created by us
print(f"The length of the list {List} using a for loop is: ", counter)

Output:

The length of the list ['Python', 'List', 'Length', 'Tutorial', 35, True, 93] using a for loop is: 
7

How to Use the Python len() Function to Determine a List's Length?

The most popular method for determining an iterable's length is to use the Python built-in len() function.

When compared to a for loop, this is simpler.

Applying the len() function requires the syntax len(listName).

The following snippet of code demonstrates how to employ the len() method to get a list's length:

Code

# Python program to show how to use a the len() function to find the length of a list

List = ["Python", "List", "Length", "Tutorial", 35, True, 93]

# Finding the length of the list
length = len(List)

# Printing the length of the list created by us
print(f"The length of the list {List} using the len() function is: ", length)

Output:

The length of the list ['Python', 'List', 'Length', 'Tutorial', 35, True, 93] using the len() function is:  7

How to Use the length_hint() Method to Determine a List's Length?

A less popular technique for determining the size of a list and all other Python iterables is length hint().

We must import the length_hint() method from the operator module to use it because it cannot be used directly.

The length hint() function's syntax is length_hint(listName).

We can see how to apply the length_hint() function from the operator module in the example below:

Code

# Python program to show how to use a the length_hint() function to find the length of a list

# Importing the required method
from operator import length_hint

# Creating a list
List = ["Python", "List", "Length", "Tutorial", 35, True, 93]

# Finding the length of the list
length = length_hint(List)

# Printing the length of the list created by us
print(f"The length of the list {List} using the length_hint() function is: ", length)

Output:

The length of the list ['Python', 'List', 'Length', 'Tutorial', 35, True, 93] using the length_hint() function is:  7

Final Thoughts

This tutorial has shown different ways to calculate a list's size using three distinct approaches: a for loop, the Python len() function, and the operator module's length_hint() method.

You might need clarification on which of these three approaches to use.

Len() is recommended since it requires less time to apply than a for loop and length_hint(). It also appears quicker than the naive for loop approach and length_hint().

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