while ($pyclinevalues[0]) {
   $pyc = $pyclinevalues[0];
   ...
   shift(@pyclinevalues);
}

##</code><code>##

while (@pyclinevalues) {
   $pyc = $pyclinevalues[0];
   ...
   shift(@pyclinevalues);
}

##</code><code>##

for my $pyc (@pyclinevalues) {
   ...
}