Regular Expressions with python
here we use re module
Regular expression is an expression which is used inorder to specify a set of strings
suppose {room,room1,room2} are public rooms available instead of specifying each rooms we can create an expression which takes less space and can specify any room
here room(1|2)? can be a regular expression where ?== multiply by 0 or 1 , (1|2)== either 1 or 2
so if we want to search room 2 we can specify it by room 2*1 where 2 is choosen from 1 or 2
there can be multiple regular expression for a set of elements
An example could be to check if in a given email field the users are entering valid emails which are in the valid email format