What is the difference between re.findall() and re.finditer() methods available in Python?

This article gives a guide on the difference between re.findall() and re.finditer() methods available in Python. The re module of Python helps in working with regular expressions.

Both the re.findall() and re.finditer() methods are used to search for patterns, but they behave differently. Let us see the differences with simple explanations and examples in this article.

Using re.findall() Method

The re.findall() helps to get a list of all matching patterns. It searches from the start or end of the given string. If we use the findall() method to search for a pattern in a given string, it will return all occurrences of the pattern. 

Example

Here is an example to show the usage of the findall() method. Here we find all occurrences of a pattern in the given text and print the returned list.

# Import re module
import re

# define text here
txt = "apple banana mango"

# define regex pattern here
pattern = r"\b\w{5}\b"

# use findall method here
matches = re.findall(pattern, txt)

# print the result
print(matches)

Output

This will create the below outcome ?

['apple', 'mango']

Using re.finditer() Method

The Python re.finditer() method returns an iterator yielding match objects for all non-overlapping matches of a pattern in a string. This method provides more detailed information about each match, such as the start and end positions within the string. Each match can be used to extract matched substrings and their positions.

Example

The following example will extract words with exactly five letters from a given text. We have used a regex pattern that matches words (\w{5}) with a word boundary (\b) to ensure only complete words are selected.

import re

txt = "apple banana mango"
pattern = r"\b\w{5}\b"

matches = re.finditer(pattern, txt)
for m in matches:
    print(m.group(), "starts at", m.start()) 

Output

This will generate the following result -

apple starts at 0
mango starts at 13

Difference between re.findall() and re.finditer()

Here is the tabular difference between re.findall() and re.finditer() functions -