BasicOfRegex.md

Regex

Introduction

• Regex is a short form of Regular Expression.
• a regular expression is denoted as RE (REs, regexes or regex pattern) are imported through re module.
• the regular expression in programing language is used to describing the string search pattern.
• A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern.
• the regular expression could tell a program to search for specific text from the string and then to print out the result accordingly.
• Regular expression supports various things like Modifiers, Identifiers, and White space characters.

How To Import regular expression in python?

• re is a built-in module in python to perform the regular expression

import re

Basic of re functions

1. findall()
2. search()
3. split()
4. sub()

Some Basic pattern requirements

IDENTIFIERS:-

\d any number
\D anything except a number
\s space
\S anything except space
\w any character
\W anything except a character
. any character but except new line
\b white space around words
\. a period(this will find out . in the given string)

MODIFIRES:-

{2,6} describing about numbers expecting result 2-6
+ Match 1 or More
? Match 0 or 1
* Match 0 or more
$ Match the end of string
^ Matching the begining of string
| either or (Example {1,3} | {6-9})
[] range or variance example [1-5],[A-Z]
{x} expecting "x" amount

White Spaces

\n newline
\t tab
\e escape
\s space
\f form feed
\r return

Note: We can use a different solution for solving the same problem