my %xmlstring = (
    QueryCId => qr/<nC[o]?ntr[a]?ctID[^>]*>\s*(\d+)\s*<\/nC[o]?ntr[a]?ctID>/s,
);

print "\nreg: ", $nsi[$index] =~ /$xmlstring{'QueryCId'}/;

$nsi[$index] =~ /$xmlstring{'QueryCId'}/ ?
    print "\nMATCH" :
    print "\nNO MATCH";

$nsi[$index] =~ /$xmlstring{'QueryCId'}/ ?
    $cid = '' :
    $cid = 'I HATE YOU';

print "\nCID should be empty: ", $cid;