Introduction To Regular Expression

• Commonly known as RegEx
• RegEx is a string containing some special characters. These characters taken together forms a pattern.
• This RegEx is used to check whether that particular pattern exists in any given string or not.

Python module re is imported to use Regular Expression methods

RegEx Functions

1.findall

• It returns a list containing all matches or an empty list in case of no match.
• It takes two parameter i.e, RegEx and String respectively.

2.Search

• It Search the string for one match.
• In case of match, it returns a MATCH OBJECT of only first match.
• In Case of no match, it returns None.
• It takes two parameter i.e,RegEx and String respectively.

3.Split

• It returns a list where the string has been split at each match.
• It takes 2-3 parameters.
• First two parameters are RegEx and String respectively.
• The Third parameter is an optional parameter,known as maxsplit parameter and takes int value as input.
• This max split parameter controls maximum number of split can be performed on the String.

4.Sub

• It looks for a match then replace it with new text string.
• It takes 3-4 parameters,4th parameter is optional.
• First 3 parameters are RegEx, newText and string respectively.
• Fourth parameter is known as count parameter and takes int value as input.
• This count parameter controls the maximum number of replacement performed on the string.