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I am new to programming and i am trying the c logic to implement in Perl for the array duplicate removal.

But i am not getting required output.Can some please give pointer where did i go wrong.

#!/usr/bin/perl -w

@x = (2,2,3,1);
$n = 3;
for ($i=0;$i<$n;$i++) {
    for ($j=$i+1;$j<$n;$j++) {
        if ($x[$i]=$x[$j]) {
            for ($k=$j;$k<$n;$k++)
            {
                print " pip";
                $x[$k] = $x[$k+1];
                print "k = $x[$k] ,j = $x[$j]\n";
                $n--;
            }
        } else {
            $j++;
        }
    }
}
print @x;
brian d foy
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user3760085
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3 Answers3

4

Your logic looks horrendous, but I do spot that you have made a rookie mistake, which may explain your program failing:

if ($x[$i] = $x[$j]) {

Here you are using the assignment operator = instead of the numerical equality operator ==. The assignment will, of course, assign the right hand parameter to the left hand parameter, which overwrites your array and corrupts your input.

As a side note, the return value of this statement is $x[$j], which may or may not be a true value, depending on your data. (for numerical data, 0 and undef will be false, all other true)

Edit:

It seems that this is not all that is wrong with your program, because it still fails. Trying to debug it does not seem like a good use of time, when deduping is so easily done in Perl, and this is a horrible way of doing it (sorry, but it is). Look at the other answers for how it is done with a hash -- make use of the fact that hash keys are unique.

This is how the dedupe function uniq is implemented in List::MoreUtils:

sub uniq (@) {
    my %seen = ();
    grep { not $seen{$_}++ } @_;
}

Quite simple, isn't it? Just return the keys which are not seen before.

TLP
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0

try using a hash for this:

my %h;
for my $i (@x) {
  $h{$i}++
}
@x = (keys %h);

this puts each value of @x into %h as the key and has the number of occurences of the element as the value in %h. if you just retrieve the keys (keys %h), you will have the distinct elements of @x, which you can then put back into @x.

Brett Schneider
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0

it does not want to change the contents when you are referring to an element of an array is good.

@x = (2,2,3,1);
@hash { @x } = 0; 
@x = keys %hash;
print @x;

#use Array::Uniq from CPAN
use Array::Uniq;
@x = (2,2,3,1);
@x = uniq @x; #or uniq sort @x;
print @x; # result:231
BLUEPIXY
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