The implicit loop is messing with your scoping, B::Deparse show you 
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = <ARGV>)) {
    chomp $_;
    our(@F) = split(/;/, $_, 0);
    use strict 'refs';
    {
        my $outfile = 'outfile.txt';
        my @result;
        my $var1 = $F[0];
        my $var2 = $F[1];
        my $var3 = $F[2];
        push @result, "$var1 $var2 $var3";
        print "Processed infile line no.: $.";
        sub END {
            print 'Array contains: ' . @result . ' element(s).';
            writeToFile(\@result, $outfile);
        }
        ;
    }
    sub writeToFile {
        my $array_ref = $_[0];
        my $filename = $_[1];
        die unless open OUTFILE, "> $filename";
        foreach $_ (@{$array_ref;}) {
            print OUTFILE $_;
        }
        close OUTFILE;
    }
    ;
}

[download]
Every time you read a line you @result is empty. The implicit loop is best left to oneliners.

See Coping with Scoping

In reply to Re: Push records to array during implicit loop and write to file by Anonymous Monk
in thread Push records to array during implicit loop and write to file by jospan

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