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

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

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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 isthere in big stringdef check(string, sub_str):
if (string.find(sub_str) == -1): print(“NO”) else: print(“YES”) driver code string = “geeks for geeks” sub_str =”geek” check(string, sub_str)

Output: YE

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))
else: print(“NO,string ‘{0}’ is not present in string {1} ” .format(MyString2, MyString1) ) Output: YES,string ‘geek’ is present in string ‘A geek in need is a geek indeed’

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