use Text::CSV;

my $csv = Text::CSV->new or die Text::CSV->error_diag;

while( my $row = $csv->getline(\*DATA) ) {
  print scalar @$row, " columns: (", join( ') (', @$row ), ")\n";
}

__DATA__
column1,column2,column3,column4,column5,column6,column7
data,data,"lname, fname mi","lname, fname mi","lname fname mi",data,data
data,data,"lname, fname mi","lname, fname mi",,data,data
data,data,"lname, fname mi",,,data,data
data,data,,,,data,data

##</code><code>##

$ ./mytest.pl
7 columns: (column1) (column2) (column3) (column4) (column5) (column6) (column7)
7 columns: (data) (data) (lname, fname mi) (lname, fname mi) (lname fname mi) (data) (data)
7 columns: (data) (data) (lname, fname mi) (lname, fname mi) () (data) (data)
7 columns: (data) (data) (lname, fname mi) () () (data) (data)
7 columns: (data) (data) () () () (data) (data)