Skip to content
Related Articles

Related Articles

Improve Article
Save Article
Like Article

Python | Check if a Substring is Present in a Given String

  • Difficulty Level : Basic
  • Last Updated : 18 May, 2020

Given two strings, check if s1 is there in s2.


Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Input : s1 = geeks s2=geeks for geeks
Output : yes

Input : s1 = geek s2=geeks for geeks
Output : yes

We can iteratively check for every word, but Python provides us an inbuilt function find() which checks if a substring is present in the string, which is done in one line.
find() function returns -1 if it is not found, else it returns the first occurrence, so using this function this problem can be solved.
Method 1: Using user defined function.

# function to check if small string is 
# there in big string
def check(string, sub_str):
    if (string.find(sub_str) == -1):
# driver code
string = "geeks for geeks"
sub_str ="geek"
check(string, sub_str)



Method 2: Using “count()” method:-

def check(s2, s1): 
    if (s2.count(s1)>0):     
s2 = "A geek in need is a geek indeed"
s1 ="geek"
check(s2, s1) 



Method 3: Using regular expressions
RegEx can be used to check if a string contains the specified search pattern. Python has a built-in package called re, which can be used to work with Regular Expressions.

# When you have imported the re module, you can start using regular expressions.
import re
# Take input from users
MyString1 =  "A geek in need is a geek indeed"
MyString2 ="geek"
# returns a Match object if there is a match anywhere in the string
if MyString2, MyString1 ):
    print("YES,string '{0}' is present in string '{1}' " .format(MyString2,MyString1))
    print("NO,string '{0}' is not present in string {1} " .format(MyString2, MyString1) )


YES,string 'geek' is present in string 'A geek in need is a geek indeed' 

My Personal Notes arrow_drop_up
Recommended Articles
Page :

Start Your Coding Journey Now!