try this:

word = 'laugh'    
string = 'This is laughing laugh'.split(" ")
index = string.index(word)

This makes a list containing all the words and then searches for the relevant word. Then I guess you could add all of the lengths of the elements in the list less than index and find your index that way

position = 0
for i,word in enumerate(string):
    position += (1 + len(word))
    if i>=index:
        break

print position  

Hope this helps.

Maybe you can use

import pytz
word = 'iran'
text = [x.lower() for x in pytz.all_timezones]
for t in text:
    if t.startswith(word):
        print(text.index(t))

List comprehension and lower() is used to make a list the elements of which are strings.

These elements are checked with startswith() and if its return value is True, its index is printed with index().

Output:

507

re.finditer(pattern, string, flags=0) takes the 1st parameter as pattern and second as string:

def findword(string, word):
    import re
    strings = string.split()
    if word in strings:
        matches = re.finditer(word, string) # see the change here
        matches_positions = [match.start() for match in matches]
        print(matches_positions)
    else:
        print("Word not found")



string=" how are you doing how do you you"
word= "you"

findword(string, word)

Output:

[9, 26, 30]