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 : yesDoes 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.
# Take input from usersMyString1 = "A geek in need is a geek indeed"
if "need" in MyString1:
print("Yes! it is present in the string")
else:
print("No! it is not present")
|
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.
# Python code# To check if a substring is present in a given string or not# input strings str1 and substrstring = "geeks for geeks" # or string=input() -> taking input from the user
substring = "geeks" # or substring=input()
# splitting words in a given strings = string.split()
# checking condition# if substring is present in the given string then it gives output as yesif substring in s:
print("yes")
else:
print("no")
|
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.
# function to check if small string is# there in big stringdef check(string, sub_str):
if (string.find(sub_str) == -1):
print("NO")
else:
print("YES")
# driver codestring = "geeks for geeks"
sub_str = "geek"
check(string, sub_str) |
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”.
def check(s2, s1):
if (s2.count(s1) > 0):
print("YES")
else:
print("NO")
s2 = "A geek in need is a geek indeed"
s1 = "geeks"
check(s2, s1) |
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.
any_string = "Geeks for Geeks substring "
start = 0
end = 1000
print(any_string.index('substring', start, end))
|
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.
a = ['Geeks-13', 'for-56', 'Geeks-78', 'xyz-46']
for i in a:
if i.__contains__("Geeks"):
print(f"Yes! {i} is containing.")
|
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.
# When you have imported the re module,# you can start using regular expressions.import re
# Take input from usersMyString1 = "A geek in need is a geek indeed"
MyString2 = "geeks"
# re.search() returns a Match object# if there is a match anywhere in the stringif re.search(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))
|
NO,string 'geeks' is not present in string 'A geek in need is a geek indeed'
