my $check_ = "chck";
my $chck_ = "check";

##</code><code>##

foreach $usr( @
#print $usr . "\n";
#print $check_.$usr;
my $check_.$usr = $cgi->param("$chck_.$usr");
print $chck_.$usr;
}

##</code><code>##

for my $user_id (@userchecklist_id) {
    my $checkbox_name = "check_$user_id";
    my $checkbox_value = $cgi->param($checkbox_name);
    print "Checkbox name:  $checkbox_name\n";
    print "Checkbox value: $checkbox_value\n";
}

##</code><code>##

my $usr = $user->id;
...
foreach $usr( @userchecklist_id) {