in reply to how to check if a particular value exist in list of files stored in an array

Your approach is one good way to do it if you do a few minor modifications. Read your first file into a hash instead of an array for easier lookup: 

my %records;
open my $fh, "<", $file1;
/^(\S+)\s/ and $records{$1}=1 while <$fh>;
close $fh;

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I am using a regular expression to find the first column in your file which seems to be simpler here and can also be used as a test. For example, empty lines will be skipped automatically this way.

Then open each of your other files in turn and check whether a given line shall be printed by doing a lookup in the hash: 

for my $file (@filelist) {
    open my $fh01, "<", $file;
    /^(\S+)\s/ and defined $records{$1} and print while <$fh01>;
    close $fh01;
}

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I have skipped all checks whether files can be opened etc. You need to add those yourself.

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Re^2: how to check if a particular value exist in list of files stored in an array
by Limbic~Region (Chancellor) on Oct 29, 2013 at 11:57 UTC
    hdb,
    Defensive programming aside, I believe that this may not completely satisfy the requirements. Perlseeker_1 wasn't clear if value should be printed once for each time it appeared in the files, if it could appear more than once, etc. I could see it being one of at least 3 choices:
    • Print once for each instance in the big files
    • Print once per big file if it appears (can still be multipl)
    • Print exactly once if it appears in any of the big files
    Assuming option 3, short-circuiting would speed things up assuming the real world case wasn't also the worst case.

    Cheers - L~R

[reply]

      Agree. But I hope that my proposal will help as a starting point even if it does not meet all the requirements.

[reply]
        Hi Experts,

        i have file called condition_file and the data in this file looks like....

        condition_file
K    01
J    02
H    03
I    04

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        I am using below code to read the file condition_file and place the values into an hash

        open F, "$condition_file" or die "File not exists";
while (<F>) {
chomp;
$records{$field1} = $field1;
}

        [download]

        I am reading list of files into array

        @array
--------
file-1
file-2
file-3
file-4

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        The content of each file

        file-1
-------
K,01,Europe,Sweden,Mace,rank1,check,01234
J,02,Australia,Sydney,Syd,rank2,chek1,01234
K,01,China,chen,mar,rank4,chack,11234
J,02,japan,Syin,yhk,ranek,chek2,21234

file-2
-------
H,03,German,Ger,hgtk,rank4,hekc,1245
I,04,Negria,neg,ghsjk,rankk1,jusk,4562
K,01,Europe1,Sweden4,Mace1,rank15,check1,12234
K,02,Europe2,Sweden3,Mace2,rank14,check2,21234

file-3
-------
H,03,German2,Ger,hgtk,rank4,hekc,1245
I,04,Negria2,neg,ghsjk,rankk1,jusk,4562
K,11,Europe5,Sweden6,Mace3,rank16,check11,42234

file-4
-------
H,16,German2,Ger,hgtk,rank4,hekc,1245
I,17,Negria2,neg,ghsjk,rankk1,jusk,4562
K,11,Europe5,Sweden6,Mace3,rank16,check11,42234

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        I need to see if the first field in condition_file exists in any of the files available in @array 

        foreach my $file_name (@array) {
open FILE, "$file_name" or die "File not exists";
while ( chomp( my ( $field1, $field2 ) = ( split /\,/, <FILE> ) ) ) {
if (exists $records{$field1}) {
$field-2 = $records{$field1};
if $field2 = $field-2;
{
print OUTPUT ( ( join ",", $field1, $field2 ), "\n" );
}}}}

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        code works like... it reads each file for example file-1, takes first two elements field1 --> K and field2 --> 01 and checks if field1 exists in records array if exists it assigns its second field to field-2, then checks if field2 and field-2 are equal, if equal then print the value to OUTPUT. This prints the data to output text file as

        Output what i got........

        output file
-------------
K,01,
J,02,
K,01,
J,02,
H,03,
I,04,
K,01,
H,03,
I,04,

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        Output i am expecting

        output file
-------------
K,01,Europe,Sweden,Mace,rank1,check,01234
J,02,Australia,Sydney,Syd,rank2,chek1,01234
K,01,China,chen,mar,rank4,chack,11234
J,02,japan,Syin,yhk,ranek,chek2,21234
H,03,German,Ger,hgtk,rank4,hekc,1245
I,04,Negria,neg,ghsjk,rankk1,jusk,4562
K,01,Europe1,Sweden4,Mace1,rank15,check1,12234
H,03,German2,Ger,hgtk,rank4,hekc,1245
I,04,Negria2,neg,ghsjk,rankk1,jusk,4562

        [download]

        The above logic is taking almost 4 hours of time to fetch the data from large/huge files

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