How can one use the print function to get the correct information?

[supriyoch_2008]

Hi PerlMonks,

I am interested to get the detailed information of the student using print function in the following script i.e. 3.pl so that the information can be printed easily on a text page. When I have used the scalar variable $result1, I have got wrong result i.e. 1. I am looking forward to Perl Monks for suggestions. I am at my wit's end to get the desrired result using print function.

Here goes the input file: rc.txt

A:50:r1
B:45:r2
C:40:r3

The script 3.pl is given below:

use warnings;
use strict;   
########################
# DATABASE Input:    ###
#################################################### 
print "\n\n Please ENTER Database Name (.txt): ";
 my $DNAfilename=<STDIN>;
 chomp $DNAfilename;   
# open the file, or exit:  
 unless (open(DNAFILE, $DNAfilename) ) {
 print "Cannot open file \"$DNAfilename\"\n\n";
 exit;}    
 my @DNA= <DNAFILE>; 
print"\n $DNAfilename Database:\n\n";
print @DNA;
print"\n";
##########################
## CODE STARTS HERE:  
##########################
 {package Student;
   sub new {    
   my ($class, $name, $age, $regd_no)=@_;
        my $objref={ NAME => $name,
                     AGE => $age,
                     REGD_NO => $regd_no  
                   };   
        return bless $objref, $class;}

    sub display
    { my ($self) = @_;
      if ($self)
        { print ' Student Name:  ', $self->{NAME},      "\n";
            print ' Age (yr):    ', $self->{AGE},       "\n";
            print ' Regd no:     ', $self->{REGD_NO},   "\n";
          }
      }
   }    
my @students;  
open (DNAFILE, '<', $DNAfilename) or die "Perl says $!"; 
while (<DNAFILE>) {
  chomp; 
  push @students, Student->new(split /:/);
}    
print"\n WELCOME to Students' Database:\n"; 
print"\n Enter the Registration Number to view the details: ";
 my $reg=<STDIN>; chomp $reg; 
 my $result1=(find_student($reg)->display());
print"\n Detailed Information for Registration No. $reg:\n
 $result1\n";   

 sub find_student
  {my ($regd_no) = @_;
  print"\n\n";
  print"\n The details of the Regn No. $reg are:\n\n";
  for (@students) {
   return $_ if $_->{REGD_NO} eq $regd_no;
  }
  return undef;  
  }  
  print"\n\n";
exit; 

The cmd shows wrong result as shown below:

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\x>cd desktop

C:\Users\x\Desktop>3.pl


 Please ENTER Database Name (.txt): rc.txt

 rc.txt Database:

A:50:r1
B:45:r2
C:40:r3


 WELCOME to Students' Database:

 Enter the Registration Number to view the details: r1


 The details of the Regn No. r1 are:

 Student Name:  A
 Age (yr):    50
 Regd no:     r1

 Detailed Information for Registration No. r1:

 1        # WRONG RESULT

C:\Users\x\Desktop> 

[golux]

Hi supriyoch_2008,

It looks like you want to return a string of text from your "display()" function (and then maybe you should call it something besides "display"). For example:

sub display
    { my ($self) = @_;
      if ($self)
        {
            my $text = " Student Name:  $self->{NAME}\n";
            $text   .= " Age (yr):      $self->{AGE}\n";
            $text   .= " Regd no:       $self->{REGD_NO}\n";
            return $text;
          } else {
            return "Not found";
         }
      }

As it is, you're just returning the last thing, which is the value of the print statement (TRUE if successful).

[Corion]

Consult the print documentation to learn about the return value of the print function.

If you want to construct a string for further processing, don't use print. Just construct the string and return it.

[CountOrlok]

Try changing:

my $result1=(find_student($reg)->display());

to:

my $result1 = find_student($reg)->display();

Update: As golux mentioned, your display function is not returning anything useful.

[supriyoch_2008]

Hi PerlMonks,

Please refer to the recent thread "How can one use the print function to get the correct information?" I have already solved the problem myself. Thanks to every Perl Monk who has helped in my endeavour.

[LanX]

OK, but why do you start a new thread?

[AnomalousMonk]

... and also, what was your solution so that other monks may benefit from it? (And if you're starting a new thread, a link back to the original thread – which was updated, of course, to reflect the fact that you arrived at a solution! – would be welcome.)

[prashantktyagi]

Why separate thread ?
Please mark same thread as solved and update solution..