How can I search a particular column in Perl?

Question

I have a text file which contains some data. I am trying to search for EA in ID column only and prints the whole row. But the code recognize all EA and prints all rows. What code I should add to satisfy the condition? Thanks Again:-)!

DATA:
Name Age ID
---------------------
KRISTE,22, EA 2008
J EA N,21,ES4567
JAK,45, EA 2008

The code prints:
KRISTE,22, EA 2008
J EA N,21,ES4567
JAK,45, EA 2008

Desired output:
KRIS,22, EA 2008
Kane,45, EA 2008,

file='save.txt';
open(F,$file)||die("Could not open $file");
while ($line=<F>){
if ($line=~ m/$EA/i) {
my @cells=($f1,$f2,$f3)= split ',',$line;
print "<TD>f1</TD>";
print "<TD>f2</TD>";
print "<TD>f3</TD>";
}

Answer 1

A combination of brian's and Jeremy's code fixes all the problems:

use strict;
use warnings;

my $file = 'save.txt';
open my $fh, "<", $file or die "Could not open $file: $!";

while ($line = <$fh>)
{
    my($f1, $f2, $f3) = split ',', $line;
    if ($f3 =~ m/EA/i)
    {
        print "<TD>$f1</TD>";
        print "<TD>$f2</TD>";
        print "<TD>$f3</TD>";
    }
}

Brian had generalized the match pattern with use CGI; and my $EA = param('keyword'); but I undid that as I didn't see it as applicable to the question.

Answer 2

You should post the actual sample program you are using to illustrate the problem. Here's your cleansed program:

use strict;
use warnings;

use CGI;

my $EA = param('keyword');

my $file = 'save.txt';
open my $fh, "<", $file or die "Could not open $file: $!";

while( $line=<$fh> ) {
   if( $line=~ m/$EA/i ) {
       my( $f1, $f2, $f3 ) = split ',', $line;
       print "<TD>$f1</TD>";
       print "<TD>$f2</TD>";
       print "<TD>$f3</TD>";
       }
   }

Here's a few things that can help you.

• Your variables need their sigils. They don't do anything without them.
• When you try to open a file and want to report an error, include the $! variable so you see what the error is.
• You can split directly to scalar variables. It's just a list assignment. You don't need the extra @cell variable.
• Give your statements some room to breathe by using some whitespace. It's free, after all.

Answer 3

You almost had it, I think this should work:

file='save.txt';
open(F,$file)||die("Could not open $file");

while ($line=<F>){
  my @cells=($f1,$f2,$f3)= split ',',$line;
  if ($f3=~ m/$EA/i) {
    print "<TD>f1</TD>";
    print "<TD>f2</TD>";
    print "<TD>f3</TD>";
  }
}

This splits the line into columns first , and then does the regex only on the third column.

BTW your code may have other problems (for example those print statements don't look like they print the values of your variables) but I don't know perl very well so I only answered your main question...

Answer 4

Rather than trying to do the CSV parsing yourself, use the excellent and efficient Text::CSV_XS . This will handle escapes and quoting.

#!/usr/bin/perl -w

use Text::CSV_XS;

my $csv = Text::CSV_XS->new();

# Skip to the data.
while(<DATA>) {
    last if /^-{10,}$/;
}

while( my $row = $csv->getline(*DATA) ) {
    print "@$row\n" if $row->[2] =~ /EA/;
}


__DATA__
Name Age ID
---------------------
KRISTE,22,EA2008
J**EA**N,21,ES4567
JAK,45,EA2008

Answer 5

或者，您可以更改正则表达式以使其与列表中的第三项匹配：

/[^,]*,[^,]*,.*EA/

Answer 6

Your regex is incorrect for what you are trying to do. Ben's solution works, although there should also be a ^ at the start, which ensures that the regex will start matching from the start of the string:

/^. ?,. ?,.*EA/

Also, your code is kinda noisy, from a perl point of view. If you want to make your code easier to read, you can do this (I'm using Ben's regex):

$f = 'save.txt';

open( F, $file );

@matches = grep { /^. ?,. ?,.*EA/ } <F>;

Now @matches will hold all your matched records, you can do what you want with them.