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Re^5: Deleting specific array elements

by JavaFan (Canon)
on Nov 26, 2008 at 17:05 UTC ( [id://726155]=note: print w/replies, xml ) Need Help??


in reply to Re^4: Deleting specific array elements
in thread Deleting specific array elements

Why? < provides scalar context to its operands.

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Re^6: Deleting specific array elements
by matrixmadhan (Beadle) on Nov 27, 2008 at 03:15 UTC
    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! :)
      There's no significant speed difference. For both the scalar and the array, the get to the integer value from the SV or AV, one has to walk a pointer and add an offset.

      It may even be that in the scalar case, perl checks IOK flag each time (to see whether it actually has a valid integer value), but that maybe optimized away.

      Anyway, there isn't much of a reason to store the length of an array in a seperate variable.

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