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

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'