Regular Expressions Interview Questions and Answers
Question - 1 : - What is the mean of Regular Expressions?
Answer - 1 : -
Regular Expressions is a pattern which is used to search string like "Search name start with a" OR "Search name end with z".
Question - 2 : - What is Regular expressions?
Answer - 2 : -
-Regular expressions is used to perform powerful and efficient text processing
-It is simple like search editors and powerful text processing language
-This is powerful pattern language
-Matching performed based on the bit pattern used for the encoding the character not based graphic representation of the character
-Regualr expressions composed with two types of characters
1)meta characters (like *)
2)litrals
Question - 3 : - How many types of Regex engines available ?
Answer - 3 : -
two types
1)DFA
2)NFA
Question - 4 : - What are good regex concerns (or) principles?
Answer - 4 : -
1)Understanding the requirement properly
2)Matching what you want
3)Keeping the Regex manageable and understandable
Question - 5 : - What is Anchors in Regular expressions?
Answer - 5 : -
Anchors not matching anything but pointing the positions in given data
There are two types of anchors
1) Simple ones (^ , $,\G ...etc)
2)Complex ones (lookbehind and lookahead)
Question - 6 : - What is the difference between ^ and \A in Regular expressions?
Answer - 6 : -
^ - Matches the starting of the line. Effecting the multiline mode
Ex: ^Bob
Bob is good
Bob is Nice
-> if used this in character class working as a negate character.
[^abc] - matching anything except a,b,c
\A - Matches the starting of the line. Not effecting the multiline mode.
Ex: \ABob - Bob is good.
Question - 7 : - What is the difference between \Z and $ in Regular expressions?
Answer - 7 : -
\Z - Matches the end of the line. Not effecting the multiline mode.
Ex: Shiva\Z
Gummadidal Shiva
Regex classes by Gummadidal Shiva
$ - Matches the end of the line.effecting the multiline mode.
Ex: Shiva$
Gummadidal Shiva
Regex classes by Shiva. Shiva is good teacher
Thanks to Shiva
[[:upper:]] - Matches capital letters is equal to [A-Z].
Ex: GUMMADIDALA shiva From Hyderabad,India
Question - 8 : - What is Character class in Regular expressions?
Answer - 8 : -
Character class always match one character.
[abc]-alwaya match either a or b or c.
Question - 9 : - What is ? (Or) optional character in Regular expressions?
Answer - 9 : -
Optional character is used to make charecter as optional, if character exist regex will match , if not ignoring the character
July?- is matching July or jul
Question - 10 : - What is the use of parentheses in Regular expressions?
Answer - 10 : -
Using parentheses perform two kind of functions
1) grouping
2) capturing