Monks,

I have input file like following:

a1a
a1a
b1b
c1c
c1c
d1d
d1d
e1e
f1f
g1g
g1g
h1h
h1h
i1i
j1j

[download]

The input file is sorted file. I want to check the lines which are present once and write in another file. Also it is huge file so i cannot use array or hash. I want to use while statement and read the file line by line and write the lines which are present once in another file.

The following code i tried, but i could not able to reach the target. So I seek your great help here.

while (<DATA>) {
    chomp;
    $curr = $_;
    $line = $.;
    if ($line == 1)
    {
        $prev = $curr;
        next;
    }
    if ($line % 2 == 0 && $line > 2 && !$flag)
    {
        $prev = $curr;
        next ;
    }
    else
    {
        $flag = 0;

    }

    if ($curr eq $prev) {
    $flag = 1;
    next;    
    }
    print "$curr\n";
$prev = $curr;
}

[download]

Here the output i need is:

b1b
e1e
f1f
i1i
j1j

[download]

In reply to Read file line by line and check equal lines by Anonymous Monk

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