#!/your/perl/here

use strict;
use warnings;

my @accounts = ("A x1 B y1 C z1 D v1 E w1 F",
                "A x2 B y2 C zzz2 D v2 E w2 F",
                "A x3 B y3 C z3 D v3 E w3 F",
                "A x4 B y4 C  D v4 E wwww4 F", # note change to C..D
                "A x5 B y5 C z5 D v5 E w5 F",
                "A x6 B y6 C z6 D v6 E    F");

my @fields = ("A", "B", "C", "D", "E", "F");

my $regex = join '\s+(\w*)\s+', @fields;

my @accounts_2 = map {[/$regex/]} @accounts;

__END__
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  DB<3> x @accounts_2
0  ARRAY(0x1ca7364)
   0  'x1'
   1  'y1'
   2  'z1'
   3  'v1'
   4  'w1'
1  ARRAY(0x1ca2b30)
   0  'x2'
   1  'y2'
   2  'zzz2'
   3  'v2'
   4  'w2'
2  ARRAY(0x1cbe7cc)
   0  'x3'
   1  'y3'
   2  'z3'
   3  'v3'
   4  'w3'
3  ARRAY(0x1cbe88c)
   0  'x4'
   1  'y4'
   2  ''              # reflects data change above
   3  'v4'
   4  'wwww4'
4  ARRAY(0x1cbf97c)
   0  'x5'
   1  'y5'
   2  'z5'
   3  'v5'
   4  'w5'
5  ARRAY(0x1cbe8bc)
   0  'x6'
   1  'y6'
   2  'z6'
   3  'v6'
   4  ''
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@fields = ("A", "B", "C", "D", "E", "F");
$splitem = join '\s*(\S*)\s*', map quotemeta $_, @fields;
print $splitem;
for my $rec (@accounts) {
    my @rowdata = $rec =~ /^$splitem\z/o or warn("misparsed $rec"), ne
+xt;
    push @accounts_2, \@rowdata;
}

for ($j = 0; $j < @accounts_2; ++$j) {
    for ($i = 0; $i < @{$accounts_2[$j]}; ++$i) {
        print ("\$accounts_2[$j][$i] = $accounts_2[$j][$i]\n");
    }
}
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