Re^3: Deleting specific array elements

[JavaFan]

Unfortunally, if the array is large, and there's a significant number of elements "\n" in the array, the repeated splicing can be slow. splice() is an O(n) operation (with n the length of the array), and that's a tight worst case bound (splice may require shifting half the array). If you have a large array, and cannot afford to copy, you can still remove the offending elements in situ:

my $j = 0;
for (my $i = 0; $i < @molecules; $i ++) {
    $molecules[$j++] = $molecules[$i] unless $molecules[$i] eq "\n";
}
splice @molecules, $j;

[matrixmadhan]

for (my $i = 0; $i < @molecules; $i ++) {

Should n't that be as



for (my $i = 0; $i < scalar(@molecules); $i ++) {

[JavaFan]

Why? < provides scalar context to its operands.

[matrixmadhan]

Thanks for that and am not aware of such a context reasoning

One more question
for (my $i = 0; $i < @molecules; $i ++) {
Instead of the above


my $num_elements = scalar(@molecules);
for (my $i = 0; $i < $num_elements; $i++) {


will that bring any performance improvement or the number of elements of an array is stored internally ( in some scalar ) and there is no need to evaluate it again ?

Thanks again for the reply! :)