Why am I getting wrong result in basic arithmetic calculations from d5.pl for $calculation1 and $calculation2?

supriyoch_2008 has asked for the wisdom of the Perl Monks concerning the following question:

Hi PerlMonks,

This has reference to my question "How can I enter the data of different variables from a text file into a perl program?" posted a few days ago. I have used the code suggested by a perlmonk and I have got correct result from d6.pl (using a little modification for data entry from the text file data.txt). But When I used the line 15 $calculation2 in d5.pl, I got wrong result. Cmd screen shows error like "Illegal division by zero at C:\Users\xyz\Desktop\d5.pl line 15". I think no zero is involved in calculation of $calculation2. I am really confused where I have made the mistake in writing the code of d5.pl. I am looking forward to suggestions from perlmonks so that d5.pl gives correct result for $calculation1 and $calculation2 i.e. 6 and 2. I have given the text file data.txt, code of d6.pl and its correct result, and also the code of d5.pl and its wrong result in calculating the $calculation1 and $calculation2.

The data file, data.txt, has the values of 9 variables (x1 to z3) in 3 separate lines:

x1=2; x2=3; x3=4;
y1=3; y2=5; y3=7;
z1=4; z2=7; z3=10;
[download]

d6.pl has the code:

#!usr/bin/perl-w
print"\n  Type the name of data file: ";
$data=<STDIN>;
chomp $data;
unless (open (DATA,$data)){
print "\n\n  Couldn't open file $data.";
}
my %vals;
while ( <DATA> ) {
  my ($identifier,$value) = split /\s*=\s*/;
  $vals {$identifier} = $value;
}
close DATA;
$calculation1=$vals{x1}*$vals{y1};
print"\n\n  1st result=$calculation1;\n\n";
exit;
[download]

d6.pl has given correct result for $calculation 1 i.e.:

C:\Users\xyz\Desktop>d6.pl

  Type the name of data file: data.txt
  1st result=6;
[download]

But d5.pl is same as d6.pl except line 15 and has the code:

#!usr/bin/perl-w
print"\n  Type the name of data file: ";
$data=<STDIN>;
chomp $data;
unless (open (DATA,$data)){
print "\n\n  Couldn't open file $data.";
}
my %vals;
while ( <DATA> ) {
  my ($identifier,$value) = split /\s*=\s*/;
  $vals {$identifier} = $value;
}
close DATA;
$calculation1=$vals{x1}*$vals{y1};
$calculation2=($vals{x1}*$vals{y1})/($vals{x2});# Line 15
print"\n\n  1st result=$calculation1;\n\n
  2nd result=$calculation2";
exit;
[download]

I have got wrong result from d5.pl for $calculation1 and $calculation2:

 C:\Users\xyz>cd desktop
C:\Users\xyz\Desktop>d5.pl

  Type the name of data file: data.txt
Illegal division by zero at C:\Users\xyz\Desktop\d5.pl line 15.
[download]

Correct results should be:

  1st result=6;
   2nd result=2;
[download]

Comment on Why am I getting wrong result in basic arithmetic calculations from d5.pl for $calculation1 and $calculation2? Select or Download Code

Replies are listed 'Best First'.
Re: Why am I getting wrong result in basic arithmetic calulations from d5.pl for $calculation1 and $calculation2? by chromatic (Archbishop) on May 07, 2012 at 05:47 UTC
If you use Data::Dumper to print your hash, you might see the bug: `use Data::Dumper; print Dumper( \%vals );` [download] You need to split your input lines on semicolons before you split on equals signs. Improve your skills with Modern Perl: the free book.	[reply] [d/l]
Re: Why am I getting wrong result in basic arithmetic calulations from d5.pl for $calculation1 and $calculation2? by Cristoforo (Curate) on May 08, 2012 at 03:30 UTC
chromatic has found the cause of your problem, but just to show another way to initialize the `%vals` hash, here is a way that doesn't split but instead, captures the key/value pairs. `#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my %vals = map /(\S+)\s=\s(\d+)/g, <DATA>; print Dumper \%vals; __DATA__ x1=2; x2=3; x3=4; y1=3; y2=5; y3=7; z1=4; z2=7; z3=10;` [download] The output of Data::Dumper is `C:\Old_Data\perlp>perl t5.pl $VAR1 = { 'y1' => '3', 'z1' => '4', 'x2' => '3', 'z2' => '7', 'x1' => '2', 'x3' => '4', 'z3' => '10', 'y2' => '5', 'y3' => '7' };` [download] Hope this is of some use, Chris	[reply] [d/l] [select]
Re: Why am I getting wrong result in basic arithmetic calulations from d5.pl for $calculation1 and $calculation2? by Cristoforo (Curate) on May 08, 2012 at 03:31 UTC
(Somehow posted twice, in error).	[reply]