How to group the values in foreach by if condition? - perl

Question

My script like this
use warnings;
use strict;
my #ar = <DATA>;
for(my $i = 0; $i<=$#ar; $i++){
$ar[$i] =~m/(\d+)$/g;
print "$ar[$i]\n" if ($& <= 15);
print "$ar[$i]\n" if ($& >100);
print "$ar[$i]\n" if ($& <40 && $& > 15);
}
__DATA__
hinsa 121
mkzin 12
mkva 34
mvakine 2
mzkev 9
mkvvz 5
mkhvzz 35
It gives the outputs but it is not group the value by if condition. and I also try this
#ar = <DATA>;
for(my $i = 0; $i<=$#ar; $i++){
$ar[$i] =~m/(\d+)$/g;
print "$ar[$i]\n" if ($& <= 15);
}
for(my $v = 0; $v<=$#ar; $v++){
$ar[$v] =~m/(\d+)$/g;
print "$ar[$v]\n" if ($& >100);
}
for(my $z = 0; $z<=$#ar; $z++){
$ar[$z] =~m/(\d+)$/g;
print "$ar[$z]\n" if ($& <40 && $& > 15);
}
In this code the second for condition is not working.
It gives the output:
mkzin 12
mvakine 2
mzkev 9
mkvvz 5
mkva 34
mkhvzz 35
I expect output is
mkzin 12
mvakine 2
mzkev 9
mkvvz 5
hisa 121
mkva 34
mkhvzz 35
How can i do it?
And also please explain, In my script 2 why the second foreach condition is not working?

Answer 1

#Hussain: When you write a perl code make sure that you use use strict; and use warnings;. I have modified your perl code and the problem with your code is you are trying to compare uninitialized $& value with a number. So it will throw a warning saying use of uninitialized $& in numeric gt (>) at so and so. For that i have modified with a scalar variable as shown below:
Input File(test.txt):
hinsa 121
mkzin 12
mkva 34
mvakine 2
mzkev 9
mkvvz 5
mkhvzz 35
Code:
use strict;
use warnings;
#Pass test.txt as an argument to the program
my $file = $ARGV[0];
open (my $fh, "<", $file) || die "cant open file";
my #ar = <$fh>;
for(my $i = 0; $i<=$#ar; $i++){
my $temp = 0;
($temp) = $ar[$i] =~ m/(\d+)/g;
print "$ar[$i]\n" if ($temp <= 15);
}
for(my $v = 0; $v<=$#ar; $v++){
my $temp = 0;
($temp) = $ar[$v] =~ m/(\d+)/g;
print "$ar[$v]\n" if ($temp > 100);
}
for(my $z = 0; $z<=$#ar; $z++){
my $temp = 0;
($temp) = $ar[$z] =~ m/(\d+)/g;
print "$ar[$z]\n" if ($temp <40 && $temp > 15);
}
close($fh);
Output:
mkzin 12
mvakine 2
mzkev 9
mkvvz 5
hisa 121
mkva 34
mkhvzz 35

Answer 2

There is no need for such convoluted code.
This program works by saving each line of the file into the appropriate element of array #groups, and printing the contents once the file has been read.
I hope you realise that lines with a value between 40 and 100 won't be printed at all?
use strict;
use warnings;
my #groups;
while (<DATA>) {
next unless /(\d+)/;
my $i;
$i = 0 if $1 <= 15;
$i = 1 if $1 > 100;
$i = 2 if $1 < 40 and $1 > 15;
push #{ $groups[$i] }, $_ if defined $i;
}
for (#groups) {
print for #$_;
print "\n";
}
__DATA__
hinsa 121
mkzin 12
mkva 34
mvakine 2
mzkev 9
mkvvz 5
mkhvzz 35
output
mkzin 12
mvakine 2
mzkev 9
mkvvz 5
hinsa 121
mkva 34
mkhvzz 35