How can I extract substrings from a string in Perl

Question

Consider the following strings   1  Scheme ID  abc-456-hu5t10  High priority         2  Scheme ID  frt-78f-hj542w  Balanced   3  Scheme ID  23f-f974-nm54w  super formula run         and so on in the above format - the parts in bold are changes across the strings       Imagine I ve many strings of format Shown above       I want to pick 3 substrings  As shown in BOLD below  from the each of the above strings    1st substring containing the alphanumeric value  in eg above it s  abc-456-hu5t10   2nd substring containing the word  in eg above it s  High priority   3rd substring containing    IF   is present at the end of the string ELSE leave it     How do I pick these 3 substrings from each string shown above  I know it can be done using regular expressions in Perl    Can you help with this

User · Answer

S   s           s           S      picks up anything which is NOT whitespace  s       0 or more whitespace characters          a literal open parenthesis          anything  non-greedy so stops on first occurrence of             a literal close parenthesis  s       0 or more whitespace characters          0 or 1 occurances of literal

User · Answer

Well  a one liner here   perl -lne  m Scheme ID  s       s           s       g amp  amp print   1  2  3   file txt   Expanded to a simple script to explain things a bit better      usr bin perl -ln                 -w   warnings                     -l   print newline after every print                                 -n   apply script body to stdin or files listed at commandline  dont print                use strict   always do this        my  regex   qr     precompile regex                                    Scheme  ID         to match beginning of line                           s                 1 or more whitespace                                                   Non greedy match of all characters up to             s                 1 or more whitespace                                                   parenthesis literal                                                      non-greedy match to the next                                           closing literal parenthesis                          s                 0 or more whitespace  trailing   is optional                           0 or 1 literal  s                                  x    x switch allows whitespace in regex to allow documentation       values trapped in  1  2  3  so do whatever you need to               Perl lets you use any characters as delimiters  i like pipes because                      they reduce the amount of escaping when using file paths            m  regex   amp  amp  print   1    2    3     alternatively if m  regex    doOne  1   doTwo  2               Though if it were anything other than formatting  I would implement a main loop to handle files and flesh out the body of the script rather than rely ing on the commandline switches for the looping

User · Answer

Long time no Perl  while  lt STDIN gt         next unless    s   S   s              s             print    1  2  3  n

User · Answer

You could use a regular expression such as the following      -a-z0-9    s           s          So for example    s    abc-456-hu5t10  High priority       s       -a-z0-9    s           s         print   1 n 2 n 3 n     prints  abc-456-hu5t10 High priority

User · Answer

String 1    input        S      s1     amp     String 2    input               s2     amp     String 3    input             s3     amp

User · Answer

This just requires a small change to my last answer   my   guid   scheme   star     line    m      The     Scheme     GUID            a-zA-Z0-9-              capture the guid                                       capture the scheme                                                    capture the star                                if it exists  x

User · Answer

You could do something like this   my  data    lt  lt END  1  Scheme ID  abc-456-hu5t10  High priority    2  Scheme ID  frt-78f-hj542w  Balanced  3  Scheme ID  23f-f974-nm54w  super formula run    END  foreach  split   n   data              Scheme ID    a-z0-9-    s             s           next    my   id  word  star      1  2  3     print   id  word  star n       The key thing is the Regular expression   Scheme ID    a-z0-9-    s             s         Which breaks up as follows   The fixed String  Scheme ID      Scheme ID     Followed by one or more of the characters a-z  0-9 or -   We use the brackets to capture it as  1     a-z0-9-      Followed by one or more whitespace characters    s    Followed by an opening bracket  which we escape  followed by any number of characters which aren t a close bracket  and then a closing bracket  escaped    We use unescaped brackets to capture the words as  2                 Followed by some spaces any maybe a    captured as  3    s

[regex] How can I extract substrings from a string in Perl?

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