Python List Length | How to Length of a List in Python

Python List Length – Table of Content

What is a list in python?

A list is a data structure that contains an ordered sequence of elements.It is a mutable or changeable object. The values in the list are called items.The values can be of different types.We can gather related set of values together that belong to a group and store them in a list. It enables us to perform any operation on all the data present in a list at once.The items should be enclosed in square brackets and separated by a comma (,). We can create a list with a combination of numbers and string characters. A list can be defined in the following ways.

ListA = [1, 2, 3, 4];ListB = ['Hi', 'Hello'];
ListC = ["Hi", "Hello"];

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Find the length of a list

The length of a list in python can be found through two methods.

Len() Method

It is a built-in function provided by python for getting the total number of items in a list, array, dictionary, etc. It takes the name of the list as an argument and returns the length of the given list. The len() method is the most commonly used method in python for finding the length of a list. Here is the syntax of the length method.

len()

is the name of the list

Let’s look at an example program.

ListA = [1, 2, 3, 4, "Hello", "World"]print ("Number of items in the list = ", len(ListA))

The output will be as follows.

Number of items in the list =  6

We can also give the list directly as an argument to the len() method.

Length = len([1, 2, 3, 4, "Hello", "World"]);
print("Number of items in the list = ", Length);

The output will be as follows.

Number of items in the list =  6

Length_hint() method

This method is not much known to programmers. It takes in a list or list name as an input argument and returns the number of items in the list. Here is a sample program that shows the use of the length_hint() method.

from operator import length_hint

ListA = [1, 2, 3, 4, "Hello", "World"]print ("Number of items in the list = ", length_hint(ListA))

The output for the above program is as follows.

Number of items in the list =  6

Naive Method

Apart from the len() method, there is another way to find the length of a list in Python. The naive approach is one of the most common methods when there is no alternative. It allows you to run the loop and count the items. Let us see its implementation :-

ListA = [1, 2, 3, 4, "Hello", "World"];print("Input List = ", str(ListA));
count = 0;
for i in ListA:
count = count + 1
print("Number of items in the list = ", count);

The output for the above program will be as follows.

Input List =  [1, 2, 3, 4, 'Hello', 'World']Number of items in the list =  6

This is the most basic method for finding the length of a list. But the len() method is always preferable to use.

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What is a list in python?

Find the length of a list

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