Mastering Regex in Perl

1. www.edureka.co/mastering-perl-scripting Mastering REGEX in Perl

2. Slide 2 www.edureka.co/mastering-perl-scripting What is Perl Benefits of Perl Advantages of using Perl scripting Starting Perl by writing the first script, Uses of Regular Expression, grep functions At the end of this module, you will be able to Objectives

3. Slide 3 www.edureka.co/mastering-perl-scripting Hi there! My name is Jose, I’m a computer consultant, techie and trainer. Students usually come to me and ask which computer language they should use in their project and why. I’m here to help Meet Mr. Jose

4. Slide 4 www.edureka.co/mastering-perl-scripting Hi There! My name is Han, I’m Quality Analyst and my manager asked me to automate the tasks. I’m confused which language to use as I have tight deadlines and want to make automation generic. I am here to meet Mr. Jose and wanted to know which language should I use for automation Meet Mr. Han

5. Slide 5 www.edureka.co/mastering-perl-scripting Hi Jose, I work for investment bank. My manager asked me to automate all my tasks. On a daily basis I interact with millions of shares. I’m confused which language should I use Hi Han, seems you need to interact with data and whenever the huge data processing comes to your mind Perl is the most suitable computer language Han is Confused!

6. Slide 6 www.edureka.co/mastering-perl-scripting Perl is one of the most popular open source interpreted programming language with a huge number of programmers, libraries and resources Perl has very powerful inbuilt regular expressions which often is the important reason when people decide to use Perl for bulk text processing Perl is platform independent and also used to generate html pages Similar to Python, PHP but, with very powerful and flexible features Inbuilt regular expression provides data filter and data transformation Perl is nicknamed "the Swiss Army chainsaw of scripting language" due to its flexibility and power What is Perl?

7. Slide 7 www.edureka.co/mastering-perl-scripting What are the Benefit of using Perl? » Perl has relatively few keywords, simple structure, and a clearly defined syntaxEasy-to-learn » Perl can run on a wide variety of hardware platforms and has the same interface on all platforms Portable » Perl provides interfaces to all major commercial databases » CPAN an archive of Perl library consist more than 20K modules Databases » One of Perl's greatest strengths is the bulk of the library is very portable and cross- platform compatible on UNIX, Windows and Mac OS Standard Library » Automatic memory management » Automatic garbage collection Memory Management » High-level data types and operations » Object-oriented programming » Easy Debugging Techniques » Scalability Others Benefits

8. Slide 8 www.edureka.co/mastering-perl-scripting About Perl Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions Perl is not an official acronym but people say it is derived from Practical Extraction and Report Language  As per the saying, frustrations of Unix shell programming led directly to the creation of Perl It is an open source and interpreted language Considered a scripting language, but is much more than that Scalable, Object Oriented and Functional Used by many Fortune 500 organizations Simply, there is nothing which Perl cannot do

9. Slide 9 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Perl has the relatively less keywords and they are many ways to do the similar thing is a philosophy of Perl Why Perl?

10. Slide 10 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Perl code is typically one-third to one-fifth the size of equivalent C++ or Java code. That means there is less to type, less to debug, and less to maintain Why Perl?

11. Slide 11 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Perl programs run unchanged on all major computer platforms. For Example- Windows, Linux, MAC OS etc. Why Perl?

12. Slide 12 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Perl comes with a large collection of prebuilt and portable functionality, known as the Standard modules. These modules supports an array of application-level programming tasks, from text pattern matching to network scripting Why Perl?

13. Slide 13 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Perl scripts can easily communicate with other parts of an application, using a variety of integration mechanisms Why Perl?

14. Slide 14 www.edureka.co/mastering-perl-scripting Less Restrictions Developer Productivity Program Portability Support Libraries Component Integration Enjoyment » Because of the ease of use and built-in toolset, Perl makes the programming more pleasurable Why Perl?

15. Slide 15 www.edureka.co/mastering-perl-scripting Users and Perl Projects » Yahoo uses Perl in many of website development and data processing » SpamAssassin is the well known SPAM filter software. It is part of the Apache Software Foundation » CiderWebmail, is an opersource product written in Perl and AJAX

16. Slide 16 www.edureka.co/mastering-perl-scripting Users and Perl Projects (Contd.) » Twiki is one of the best-known wiki software with an orientation to support companies. It is built primarily by the company with the same name that also provides cloud-based hosted Twiki service » Bugzilla is the well known bug-tracking system developed by and for Mozilla. It is used in quite a lot of companies

17. Slide 17 www.edureka.co/mastering-perl-scripting Traditional Uses of Perl Internet Scripting System Utilities Web ScrapingDatabase Programming Ad Targeting Text Processing

18. Slide 18 www.edureka.co/mastering-perl-scripting Traditional Uses of Perl (Contd.) Request Result NetworkCRM LOB ERP ETL Data Warehouse ETL Processing Network Programming

19. Slide 19 www.edureka.co/mastering-perl-scripting Write a First Program  We can use any editor to create a scripts on Windows and vi editor on Linux  The extension of the script is .pl  Perl executable statements end with semicolons (;)  Perl is case-sensitive  Free form – whitespaces are ignored  Comment begin with # (pound sign) – may be anywhere, not just beginning of line  Perl also support multiline comment through POD (Plain Old Documentation)  Using POD we can add the documentation in the scripts, these statements are not treated as executable statements  __END__ is one of the special literal which is the logical end of the program

20. Slide 20 www.edureka.co/mastering-perl-scripting Write a First Program (Contd.)  To execute the script, invoke the script using perl <script name>  For LINUX users – you can execute the script while adding the she bang line (the interpreter address at the very first line of the script) to make them self executable Example D:Edureka > perl helloWorldDemo.pl D:Edureka > helloWorldDemo.pl

21. Slide 21 www.edureka.co/mastering-perl-scripting  Regular Expression is a set of characters together form the search pattern  Main use of regular expression is to match patterns in any string forms  The other use of regular expression ‘find and replace feature’  Regular expression forms the generic pattern for the string matching with the help of pre-defined wildcard characters  Many language provide regular expression capabilities, some language have it inbuilt and other are having regular expression libraries  Regular expression is also known by regex or regexp  In Perl regex is inbuilt, hence it is pretty good in performance What is Regular Expression?

22. Slide 22 www.edureka.co/mastering-perl-scripting Real World – Regular Expression I wish, if I could have the software which filter all the phone call starting with +140

23. Slide 23 www.edureka.co/mastering-perl-scripting Match Operator We have match operator which matches the regex available in the string  =~ (assignment operator followed by tilda operator is use for regex matching)  !~ (Negation operator followed by tilda operator is use for regex un-matching) ~ operator after assignment operator perform the regex matching, REGEX are case sensitive, m character in matching regex is optional

24. Slide 24 www.edureka.co/mastering-perl-scripting A Word Match – Example Output Example

25. Slide 25 www.edureka.co/mastering-perl-scripting The First Wildcard Wildcards (are also called as quantifiers) are the operator symbols which have specific meaning inside regular expression For example: . (Dot or period) matches any character, digit, alphanumeric character except newline character (n).

26. Slide 26 www.edureka.co/mastering-perl-scripting Match Operator itself In many cases, user may wants to match the operator symbol itself in the regular expression. We can suppress the wild cards and special characters itself by backslash () Output Example

27. Slide 27 www.edureka.co/mastering-perl-scripting Capturing and Grouping Perl regex remember a group of strings which being the part parentheses in the regular expression Inside regex, these groups are refer by back references. They are 1, 2,3 and so on.. Outside regex, these groups are refer by special variable $1, $2, $3 and so These groups can also be fetched by variables assignment in list context called as capturing

28. Slide 28 www.edureka.co/mastering-perl-scripting Back References Example Output Example

29. Slide 29 www.edureka.co/mastering-perl-scripting Substitution The another Perl operator that uses regular expressions allows us to provide find and replace feature Regex are Greedy, means it will try to match as much it can! This is called as substitution

30. Slide 30 www.edureka.co/mastering-perl-scripting Modifier ‘i’ and ‘g’ ‘i’ modifier make the REGEX case insensitive ‘g’ modifier is for global search

31. Slide 31 www.edureka.co/mastering-perl-scripting Modifier ‘s’ and ‘m’ ‘m’ modifier ^ and $ match more than once inside a string. ‘s’ modifier make . to match n as well

32. Slide 32 www.edureka.co/mastering-perl-scripting Modifier ‘x’ ‘x’ modifier white spaces in the REGEX are ignored. This modifier is used for clean syntax

33. Slide 33 www.edureka.co/mastering-perl-scripting Greedy Property of REGEX Wildcards Whenever Perl REGEX sees '*' or '+‘ or ‘?’ or {a,b} it will matches as much as it can This property is greedy property of regex wildcards Sometimes it’s an issue as substitute replace the matched string

34. Slide 34 www.edureka.co/mastering-perl-scripting Other Wildcards These wildcard characters do not matches themselves. Until and unless they suppressed by backslash Following are the other wildcards: Wildcard Meaning * matches Zero or more occurrence of previous character/s + matches One or more occurrence of previous character/s ? matches Zero or One occurrence of previous character/s

35. Slide 35 www.edureka.co/mastering-perl-scripting Wildcards Examples REGEX Matches AbC* It matches A followed by b followed by either Zero or more occurrence of C. i.e. Ab, AbC, AbCCCC, AbCCCCCCCCCCCC AbC+ It matches A followed by b followed by minimum one or more occurrence of C i.e. AbC, AbCCCCCCCC, AbCCC AbC? It matches A followed by b followed by one or Zero occurrence of C. i.e. Ab, AbC Ab(cd)* It matches A followed by b followed by either Zero or more occurrence of cd i.e. Ab, Abcd, Abcdcd Ab(cd)+ It matches A followed by b followed by minimum one or more occurrence of cd i.e. Abcd, Abcdcd Ab(cd)? It matches A followed by b followed by either one or zero occurrence of cd i.e. Abcd, Ab

36. Slide 36 www.edureka.co/mastering-perl-scripting Combine Multiple Wildcards REGEX Matches Ab+C* It matches A followed by minimum one or more occurrence of b followed by either Zero or more occurrence of C. i.e. Ab, AbC, AbbCCC. AbbCCCCCCCCCC A.C+ It matches A followed by any character followed by minimum one or more occurrence of C i.e. AZC, AzCCC. AECCCCCCCCCCC ..C? It matches any two characters followed by b followed by one or Zero occurrence of C. i.e. Ab, AbC <.*> It matches anything inside tags <> i.e. <HTML>, <TAGS> ( .+ ) It matches minimum one character inside brackets cd i.e. (Abcd), (a) ab+c? It match a followed by one or more b followed by zero or one c. i.e. "abbbbc" or "abc", but not "ac"

37. Slide 37 www.edureka.co/mastering-perl-scripting Character Class in Regex Character class is the set of any characters, digits or alphanumeric characters While using the character class in Regex, it says any single character from the set In character class we put a list of the characters in set inside square brackets like: REGEX Matches [abc] It matches any string which has either ‘a’ or ‘b’ or ‘c’ [abcdefghijklmnopqrstuvwxyz] It matches any string which has either ‘a’ or ‘b’ or ‘c’ or so on till ‘z’ [a-z] It matches any string which has either ‘a’ or ‘b’ or ‘c’ or so on till ‘z’ [0-9] It matches any string which has 0 or 1 or 2 or 3 till 9 [a-zA-Z0-9] It matches any string which has characters from a-z and A-Z and 0-9 [a-z_] It matches any string which has characters from a-z or _ (underscore)

38. Slide 38 www.edureka.co/mastering-perl-scripting Negate the Character Class ^ (carat) symbol inside character class is used to negate the character class in regex  If we put the carat within the character class in Regex, it says none of the single character from the set Here are few examples: REGEX Matches [âbc] It matches any string which has neither ‘a’ nor ‘b’ nor ‘c’ [âbcdefghijklmnopqrstuvwxyz] It matches any string which has neither ‘a ‘ or ‘b’ or ‘c’ or so on till ‘z’ [â-z] It matches the string which has neither ‘a’ or ‘b’ or ‘c’ or so on till ‘z’ [âeiou] It matches the string which has no vowels [lL][âbc] It matches the string has ‘l’ or ‘L’ should not followed by ‘a’ nor ‘b’ nor ’c’ [â-z_] It matches the string doesn’t have a-z or _ (underscore)

39. Slide 39 www.edureka.co/mastering-perl-scripting Combine Character Class with Wildcards REGEX Matches [aA][0-9]+ It matches any string which has ‘a’ or ‘A’ followed by any number and occurrence can any number of times A+.[.?] It matches any string which has ‘A’ any number of times followed by any character followed by either ‘.’ or ‘?’ a[bc] It matches any string which has ‘a’ followed by either ‘b’ or ‘c’ A[abc]? It matches the string which has ‘A’ followed by zero or one occurrence of either ‘a’ or ‘b’ or ‘c’ [a-z_.]@ It matches the string has ‘a’ to ‘z’ or ‘_’ or ‘.’ followed by ‘@’

40. Slide 40 www.edureka.co/mastering-perl-scripting Character Class - Shortcuts Character classes can also be represent by shortcuts Following are the examples: Shortcut Say Meaning s Any space, tab or new line characters [ tn] S Other than space, tab or newline character [^tn] d Any digit [0-9] D Other than digit [^0-9] w Digits, characters or _ (underscore) [a-zA-Z0-9_] W Other than digit, character or _ [^a-zA-Z0-9_]

41. Slide 41 www.edureka.co/mastering-perl-scripting Shortcuts with Wildcards Shortcuts can also be used with wildcards Following are the examples: Shortcut Say Meaning s+ Any number of space, tab or new line characters [ tn]+ S+ Other than space, tab or newline character any number of times [^tn]+ d+ Any digit any number of times [0-9]+ D+ Other than digit any number of times [^0-9]+ w+ Digits, characters or _ (underscore) any number of times [a-zA-Z0-9_]+ W+ Other than digit, character or _ any number of times [^a-zA-Z0- 9_]+

42. Slide 42 www.edureka.co/mastering-perl-scripting Meta Characters Shortcut Say Meaning ^ ^ful Should start with a string i.e. matches ‘ful’ but not ‘wonderful’ $ ful$ Should be ended with a string i.e. matches ‘wonderful’ but not the word ‘Fultron’ {a,b} Abc{1,2} Abc{1} It matches the string has ‘A’ followed by ‘B’ followed by minimum one occurrence if ‘c’ and maximum 2 occurrence. (…) (w+) Grouping will be discuss in later slides ? Backspace – suppress the special meaning of quantifiers. | Black|white Black or White in the string

43. Slide 43 www.edureka.co/mastering-perl-scripting Meta Symbols Shortcut Say Meaning A Aful Should start with a string i.e. matches ‘ful’ but not ‘wonderful’ Z FulZ Should be ended with a string i.e. matches ‘wonderful’ but not the word ‘Fulltron’ cA cA Match control A, cB Match control B Q and E Q What is your name?E Quotes the meta characters till E (? Is question mark here not the quantifier) b bfulb Looks for exact word ful B BFulB Opposite of b n and t t Match the n (new line) and t(tab character)

44. Slide 44 www.edureka.co/mastering-perl-scripting All in One Example REGEX Matches /full/ Matches ‘full’, ‘Wonderful’ and ‘Fultron’ /Ao+/ Matches Ao, Aoo, Aoooo /A(oh)*/ Matches A, Aoh, Aohoh /Yahoo{1,3}/ Matches Yahoo, Yahooo, Yahoooo /Edurekas?/ Matches Edureka, Edurekas /Checks+mates/ Matches Check followed by spaces followed mates /$10/ Matches $10, $100, $101

45. Slide 45 www.edureka.co/mastering-perl-scripting All in One Example REGEX Matches /full/ Matches ‘full’, ‘Wonderful’ and ‘Fultron’ /Ao+/ Matches Ao, Aoo, Aoooo /A(oh)*/ Matches A, Aoh, Aohoh /Yahoo{1,3}/ Matches Yahoo, Yahooo, Yahoooo /Edurekas?/ Matches Edureka, Edurekas /Checks+mates/ Matches Check followed by spaces followed mates /$10/ Matches $10, $100, $101

46. Slide 46 Your feedback is important to us, be it a compliment, a suggestion or a complaint. It helps us to make the course better! Please spare few minutes to take the survey after the webinar. www.edureka.co/mastering-perl-scripting Survey

47. Slide 47 Course Url

Mastering Regex in Perl

Mastering Regex in Perl

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