in reply to insert null in missing places of csv

To process CSV, use the Text::CSV_XS module (I guess your CSV is a bit more complicated than shown in the example). Read the input line by line, replace each zero-length entry with the "NULL" string.

#!/usr/bin/perl
use warnings;
use strict;

use Text::CSV_XS;

my $csv = 'Text::CSV_XS'->new({binary => 1});
open my $CSV, '<', shift or die $!;

while (my $row = $csv->getline($CSV)) {
    $csv->say(\*STDOUT, [ map length ? $_ : 'NULL', @$row ]);
}

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

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Re^2: insert null in missing places of csv
by Tux (Canon) on Feb 19, 2016 at 13:51 UTC

    Note that this approch changes both 1,2,,3,4 and 1,2,"",3,4 to 1,2,NULL,3,4.

    The safe way would be

    $ cat test.pl

use 5.18.2;
use warnings;
use Text::CSV_XS qw( csv );

csv (in => csv (
        in             => *ARGV,
        blank_is_undef => 1,
        on_in          => sub { $_ //= "NULL" for @{$_[1]}; },
        ),
     );

$ cat test.csv
1,2,,3,4
1,2,"",3,4

$ perl test.pl test.csv
1,2,NULL,3,4
1,2,,3,4

    [download]

    Enjoy, Have FUN! H.Merijn
[reply]
[d/l]
[select]

      awesome

      this meets my requirement, all other suggestions are even replacing 0 with NULL.

      Could you please suggest me how can i call csv file directly inside the script instead of calling it on command prompt ?

      This is what I am running using your input:

      #!/usr/bin/perl
#use strict;
use warnings;
use Text::CSV_XS qw( csv);


csv (in => csv (
        in             => *ARGV,
        blank_is_undef => 1,
        on_in          => sub { $_ //= "NULL" for @{$_[1]}; },
        ),
     );

      [download]
      perl test.pl 1.csv

      all i need is to call 1.csv inside test.pl only

      perl test.pl
[reply]
[d/l]
[select]

        It's in the docs:

        # use command line args
in => *ARGV,

# use a file
in => "1.csv",

        [download]

        Enjoy, Have FUN! H.Merijn
[reply]
[d/l]

        In Perl the command line arguments are automatically transferred into the special array @ARGV. All you need to do is replace @ARGV in your code with some other static array of your choice.

[reply]
        > all other suggestions are even replacing 0 with NULL.

        Mine doesn't. Or do you think that length 0 is false?

        ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

        [download]
[reply]
[d/l]
        ... all other suggestions are even replacing 0 with NULL.

        The regex solution does not!

        Give a man a fish:  <%-{-{-{-<

[reply]
[d/l]

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