Skip to content
Related Articles

Related Articles

Python Regex – re.MatchObject.start() and re.MatchObject.end() functions
  • Difficulty Level : Easy
  • Last Updated : 20 Aug, 2020

In this article, we are going to see re.MatchObject.start() and re.MatchObject.end() regex methods.

re.MatchObject.start() 

This method returns the first index of the substring matched by group.

Syntax: re.MatchObject.start([group])

Parameter:

  • group: (optional) group defaults to zero (meaning the whole matched substring). Return -1 if group exists but did not contribute to the match. 

Return: Index of start of the substring matched by group.

AttributeError: If a matching pattern is not found then it raise AttributeError.

re.MatchObject.end()

This method returns the last index of the substring matched by group.

Syntax: re.MatchObject.end([group])



Parameter:

  • group: (optional) group defaults to zero (meaning the whole matched substring). Return -1 if group exists but did not contribute to the match. 

Return: Index of end of the substring matched by group.

AttributeError: If a matching pattern is not found then it raise AttributeError.

Consider the below example:

Example 1:

Python3




import re
  
# getting the match of the the string
search_pattern = re.search('\d+',
                           '1234')
  
""" 
d: stands for integer
+: means a consecutive set of 
characters satisfying a condition. 
Hence d+ will match consecutive 
integer string 
"""
  
print(search_pattern.string)
  
print(search_pattern.start())
  
print(search_pattern.end())

Output:

1234
0
4

Let’s understand the code. In the third line of the code we use the re.search() method to find a match in the given string(‘1234‘) the ‘d indicates that we are searching for a numeric character and the ‘+‘ indicates that we are searching for continuous numeric characters in the given string. The result we get is a re.MatchObject which is stored in search_pattern. If you print search_pattern.string you will get ‘1234’ as output. 

In the above example, the search_pattern.start() returns value 0 as the index of the first element of the matched string in the given string is 0 and the search_pattern.end() returns 4 that is the end index after the end of the string. 

Example 2:

Python3




import re
  
# getting the match of the the string
search_pattern = re.search('\d+',
                           'abcd')
""" 
d: stands for integer
+: means a consecutive set of characters 
satisfying a condition. 
Hence d+ will match consecutive 
integer string 
"""
  
print(search_pattern.start())
  
print(search_pattern.end())

Output:

Traceback (most recent call last):
  File "/home/4f904f4b53a786e10faa03122533f96b.py", line 13, in 
    print(search_pattern.start())
AttributeError: 'NoneType' object has no attribute 'start'

 Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.  

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up
Recommended Articles
Page :