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

Examples:

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):
		print("NO")
	else:
		print("YES")
			
# driver code
string = "geeks for geeks"
sub_str ="geek"
check(string, sub_str)

Output:

YES     

Method 2: Using “count()” method:-

def check(s2, s1):
	if (s2.count(s1)>0):	
		print("YES")
	else:
		print("NO")
			
s2 = "A geek in need is a geek indeed"
s1 ="geek"
check(s2, s1)

Output:

YES       

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"

# re.search() returns a Match object if there is a match anywhere in the string
if 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) )

Output:

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