python index of last occurrence in string code example

Example 1: find last appearance python

>>> s = 'hello'
>>> s.rfind('l')
3

Example 2: how to find the last occurrence of a character in a string in python

original_string = "sentence one. sentence two. sentence three"

last_char_index = original_string.rfind(".")
new_string = original_string[:last_char_index] + "," + original_string
print(new_string)
"sentence one. sententce two, sentence three"