How do I search a Perl array for a matching string

Question

What is the smartest way of searching through an array of strings for a matching string in Perl   One caveat  I would like the search to be case-insensitive  so  aAa  would be in   aaa   bbb

User · Answer

If you will be doing many searches of the array  AND matching always is defined as string equivalence  then you can normalize your data and use a hash   my  strings   qw  aAa Bbb cCC DDD eee     my  string lut     Init via slice   string lut  map uc   strings            or use a for loop       for my  string    strings               string lut  uc  string      undef            Look for a string   my  search    AAa    print    string            exists  string lut  uc  string    IS     is NOT           in the array n     Let me emphasize that doing a hash lookup is good if you are planning on doing many lookups on the array   Also  it will only work if matching means that  foo eq  bar  or other requirements that can be met through normalization  like case insensitivity

User · Answer

For just a boolean match result or for a count of occurrences  you could use   use 5 014  use strict  use warnings  my  foo   hello    world    foo    bar    hello world    HeLlo    my  patterns join      foo   for my  str  qw quux world hello hEllO         my  count map  m   str  i   foo      if   count            print  I found   str   count time s  in   patterns  n         else           print  I could not find   str  in the pattern list n             Output   I could not find  quux  in the pattern list I found  world  1 time s  in  hello world foo bar hello world HeLlo  I found  hello  2 time s  in  hello world foo bar hello world HeLlo  I found  hEllO  2 time s  in  hello world foo bar hello world HeLlo    Does not require to use a module  Of course it s less  expandable  and versatile as some code above  I use this for interactive user answers to match against a predefined set of case unsensitive answers

User · Answer

I guess   foo     aAa    bbb     bar   grep   aaa i   foo   print join      bar    would do the trick

User · Answer

Perl 5 10  contains the  smart-match  operator     which returns true if a certain element is contained in an array or hash  and false if it doesn t  see perlfaq4    The nice thing is that it also supports regexes  meaning that your case-insensitive requirement can easily be taken care of   use strict  use warnings  use 5 010   my  array    qw aaa bbb   my  wanted    aAa    say    wanted  matches   if   wanted i     array      Prints   aAa  matches

User · Answer

usr bin env perl  use strict  use warnings  use Data  Dumper   my  bar   qw aaa bbb   my  foo   grep   aAa i   bar   print Dumper   foo

User · Answer

Perl string match can also be used for a simple yes no   my  foo   hello    world    foo    bar     if    foo       bhello b        print  found     else      print  not found

User · Answer

It depends on what you want the search to do    if you want to find all matches  use the built-in grep   my  matches   grep    pattern     list of strings   if you want to find the first match  use first in List  Util   use List  Util  first     my  match   first    pattern     list of strings   if you want to find the count of all matches  use true in List  MoreUtils   use List  MoreUtils  true   my  count   true    pattern     list of strings   if you want to know the index of the first match  use first index in List  MoreUtils   use List  MoreUtils  first index    my  index   first index    pattern     list of strings   if you want to simply know if there was a match  but you don t care which element it was or its value  use any in List  Util   use List  Util 1 33  any   my  match found   any    pattern     list of strings     All these examples do similar things at their core  but their implementations have been heavily optimized to be fast  and will be faster than any pure-perl implementation that you might write yourself with grep  map or a for loop     Note that the algorithm for doing the looping is a separate issue than performing the individual matches   To match a string case-insensitively  you can simply use the i flag in the pattern    pattern i   You should definitely read through perldoc perlre if you have not previously done so

[perl] How do I search a Perl array for a matching string?

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