Grep to find item in Perl array

Question

Every time I input something the code always tells me that it exists  But I know some of the inputs do not exist  What is wrong      usr bin perl   array    lt  gt   print  Enter the word you what to match n   chomp  match    lt STDIN gt     if  grep  match   array         print  found it n

User · Answer

This could be done using List  Util s first function   use List  Util qw first    my  array   qw foo bar baz   print first      eq  bar     array    Other functions from List  Util like max  min  sum also may be useful for you

User · Answer

You can also check single value in multiple arrays like   if  grep   match    array   array one   array two   array Three        print  found it n

User · Answer

I could happen that if your array contains the string  hello   and if you are searching for  he   grep returns true  although   he  may not be an array element   Perhaps   if  grep    match     array   more apt

User · Answer

You seem to be using grep   like the Unix grep utility  which is wrong   Perl s grep   in scalar context evaluates the expression for each element of a list and returns the number of times the expression was true  So when  match contains any  true  value  grep  match   array  in scalar context will always return the number of elements in  array   Instead  try using the pattern matching operator   if  grep   match    array        print  found it n

User · Answer

The first arg that you give to grep needs to evaluate as true or false to indicate whether there was a match  So it should be     note that grep returns a list  so  matched needs to be in brackets to get the    actual value  otherwise  matched will just contain the number of matches if  my   matched    grep    eq  match   array        print  found it   matched n       If you need to match on a lot of different values  it might also be worth for you to consider putting the array data into a hash  since hashes allow you to do this efficiently without having to iterate through the list     convert array to a hash with the array elements as the hash keys and the values are simply 1 my  hash   map       gt  1   array     check if the hash contains  match if  defined  hash  match         print  found it n

User · Answer

In addition to what eugene and stevenl posted  you might encounter problems with using both  lt  gt  and  lt STDIN gt  in one script   lt  gt  iterates through   concatenating  all files given as command line arguments   However  should a user ever forget to specify a file on the command line  it will read from STDIN  and your code will wait forever on input

[perl] Grep to find item in Perl array

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