Hi All,

i want to know how to calculate number of sub String available with in a string in python

You most explain better,there are several scenarios for this.
Look at this.

>>> s = 'foo bar foo bar foo'
>>> len(s.split())
5

So 5 substring in s.

>>> s[:2]
'fo'

"fo" is a substring of s.

import re
[m.start() for m in re.finditer('oo', s)]
[1, 9, 17]

"oo" is substring,to find all i use regex.

>>> s = 'ttt'
>>> [m.start() for m in re.finditer('(?=tt)', s)]
[0, 1]

Find overlapping matches

Also look at build in string function can help.

>>> help(s.find)
Help on built-in function find:

find(...)
    S.find(sub[, start[, end]]) -> int
    
    Return the lowest index in S where substring sub is found,
    such that sub is contained within s[start:end].  Optional
    arguments start and end are interpreted as in slice notation.
    
    Return -1 on failure.

>>>