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

In this article, we will cover how to check if a Python string contains another string or a substring in Python. Given two strings, check if a substring is there in the given string or not. 

Example 1: Input : Substring = "geeks" 
           String="geeks for geeks"
Output : yes
Example 2: Input : Substring = "geek"
           String="geeks for geeks"
Output : yes

Does Python have a string containing the substring method

Yes, Checking a substring is one of the most used tasks in python. Python uses many methods to check a string containing a substring like, find(), index(), count(), etc. The most efficient and fast method is by using an “in” operator which is used as a comparison operator. Here we will cover different approaches like:

• Using the if… in 
• Checking using the split() method
• Using find() method
• Using “count()” method
• Using the index() method
• Using  __contains__” magic class.
• Using regular expressions 

Method 1: Check substring using the if… in.

Yes! it is present in the string

Method 2: Checking substring using the split() method

Checking if a substring is present in the given string or not without using any inbuilt function. First split the given string into words and store them in a variable s then using the if condition, check if a substring is present in the given string or not.

yes

Method 3: Check substring using the find() method

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. 

YES

Method 4: Check substring using “count()” method

You can also count the number of occurrences of a specific substring in a string, then you can use the Python count() method. If the substring is not found then “yes ” will print otherwise “no will be printed”.

NO

Method 5: Check substring using the index() method

The .index() method returns the starting index of the substring passed as a parameter. Here “substring” is present at index 16.

Output:

16

Method 6: Check substring using the “__contains__” magic class.

Python String __contains__(). This method is used to check if the string is present in the other string or not. 

Yes! Geeks-13 is containing.
Yes! Geeks-78 is containing.

Method 7: Check substring 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. 

NO,string 'geeks' is not present in string 'A geek in need is a geek indeed' 

Method: Using list comprehension 

['yes']

Method: Using lambda function

['yes']

Method: Using countof function 

['yes']