regular expressions the replace method of strings is used to replace all occurrences of one string with anotherand the index method is used to find the first occurrence of substring in string but sometimes you need to do more sophisticated search or replace for exampleyou may need to find all of the occurrences of string instead of just the first one or maybe you want to find all occurrences of two letters followed by number or perhaps you need to replace every 'quthat is at the start of word with 'quthis is what regular expressions are for utilities for working with regular expressions are found in the re module there is some syntax to learn in order to understand regular expressions here is one example to give you an idea of how they workimport re print(re sub( '([lrud])(\ +''**''locations and full ')locations **and **full this example replaces any occurrence of an lruor followed by one or more digits with '*** introduction sub the sub function works as followssub(patternreplacementstringthis searches through string for pattern and replaces anything matching that pattern with the string replacement all of the upcoming examples will be shown with subbut there are other things we can do with regular expressions besides substituting we will get to those after discussing the syntax of regular expressions