Python: 7 Ways to Find the Length of a String

This concise, example-based article will walk you through several different ways to find the length (the number of characters) of a given string in Python. Each approach will be explained briefly, followed by a code example. I assume that you already have some basic understanding of the programming language, so I won’t waste your time with meaningless words (like talking about the history of Python). Let’s get to the point!

Using the len() function (recommended)

len() is a built-in function of Python. It returns the length of a string or any other iterable object.

Example:

text = "Welcome to Sling Academy"
length = len(text)
print(length)

Output:

24

In general, this one is the most simple, elegant, and efficient approach to getting the length of a Python string.

Using a for loop

By using a for loop, you can iterate over the string and count the characters one by one.

Example:

my_string = "Fighting dragons is my hobby!"

length = 0 
for letter in my_string:
    length += 1

print(f"The length of my_string is {length}")

Output:

The length of my_string is 29

Using list comprehension

List prehension is a powerful and beautiful feature of Python that other popular programming languages like JavaScript or Dart do not have. You can take advantage of it to get the job done.

Example:

text = "He thrusts his fists against the posts and still insists he sees the ghosts"

length = len([char for char in text])
print(length)

Output:

75

Using recursion

A recursive function is a function that calls itself. We can implement a recursive function to count the length of a given string. This is like using something as big and expensive as a rocket to light a bonfire, but it will give you more solid muscles in programming with Python.

Example:

def get_length(text):
    if text == "":
        return 0
    else:
        return 1 + get_length(text[1:])

length = get_length("Sling Academy is a website for learning Python.")
print(length) 

Output:

47

Using regular expressions

You can utilize the re module to find the length of the string by matching all characters using a regular expression pattern. Even though it seems that this technique is much heavier than necessary, it’s worth knowing.

import re

text = "Welcome to slingacademy.com"
matches = re.findall(".", text)
length = len(matches)
print(length)  

Output:

27

Using the reduce() function

The reduce() function from the functools module can be used to perform a cumulative operation on a sequence. In this case, we can use it, to sum up the characters in the string.

Example:

from functools import reduce

text = "No more boring foo-bar examples"
length = reduce(lambda count, char: count + 1, text, 0)
print(length)

Output:

31

Using a while loop

We can use a while loop to count the number of characters in a given string by iterating through it until no more characters are left.

Example:

# Define a reusable function
def get_length(str):
    count = 0
    while str[count:]:
        count += 1
    return count

print(get_length("Goodbye World!"))

Output:

14

The tutorial ends here. Happy coding & enjoy your day!