find substring python

 find substring():

• The find substring is used to find the substring from the string.
• Substring is the piece of characters from the string.
• If the string consists of the given string then it returns the index number of the substring. 
• The string must be enclosed with single or double-quotes.
• It returns -1 if the substring does not found instead of an error.
• find() has 3 parameters,they are:

1. value: The value to be search
2. start:  from where to search
3. end:  from where to stop searching.

Syntax: str.find(value,start,end)

#write a python code to demonstrate the find substring function.

1. txt="learning is a life time process"
2. txt=txt.find("i")
3. print(txt)
4. s="apple"
5. s=s.find("b")
6. print(s)

Output: 5

              -1