Though, it seems you forgot to post the code you've worked on. I won't assume you wanted someone else to write it for you, so I'll give you some places to look. Then when you have some code that you have written, and have a problem you can ask a question here. (right after you read this)

• Go take a look at open about reading the file
• Look at foreach loops to go over the lines in the file
• Look at split to get the number and name
• Read about Hashes(associative arrays) to store your results
• perlop will tell you how to evaluate 'less than'
• And finally reading print will show you how to print your results

Thank you grep, but my problem is exactly on how to compare the numbers.
Assuming, for example, that I have the code:


open FILE, $my_file;
while (<FILE>)
{
$_=~/(.*)\t(.*)/;
$name=$1;
$code=$2;

$hash{$name} = $code;

}
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That is as far as I can go...

OK.

Couple of things first.


• Use strict and warnings
• Check to see if your open succeeds
• Use split not a regex when you want to split
• Indent your code - It makes reading the code easier on you and us
So your code should look something like (untested):

use strict;
use warnings;

open FILE, $my_file or die "Can't open $my_file\n";
my %hash;
while (<FILE>) {
  my ($name, $code) = split(/\t/);
 
}
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Now you have some of the problems fixed. Now you need to test what's in the hash and $code.

One thing to remember is, that if you have not assigned a value to the hash for that key you'll get undef returned, which evaluates to 0 numerically. Since you are looking for the lowest number you'll want avoid the undef. So check the value from your hash with defined first. If you see that it is not defined, then you know to assign the value of $code whatever it is.

  # Still untested
  if ( !defined( $hash{$name} ) ) {
    $hash{$name} = $code;
  }
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If you have a value defined then check to see whats larger

  # Still untested
  if ( !defined( $hash{$name} ) or $code < $hash{$name} ) {
    $hash{$name} = $code;
  }
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grep

...

if (!exists $hash{$name}) {
    # unconditionally assign the first entry
    $hash{$name} = $code;
} else {
    # assign further entries only if smaller... 
    $hash{$name} = $code if $code < $hash{$name};
}
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Yes there is - there are many ways in fact. To get started you need to take a look at open, close, perldata (hashes in particular), perlsyn (while loops) and perlop (the diamond operator: '<FILEHANDLE>'), then take a stroll through the Tutorials section here.

When you've done all that and written your first attempt at the code, come back here with any problems you might have.

sort -n +1  a_file > a_sorted_file
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sort -n +1  a_file | head -5 > first_five_sorted
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jim     5
nick    29
george  12
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