I am trying to splice the array on the copy and not original array But looks like the loop ends before it can read the next 6 in the list
It's not the loop ending prematurely, it is wrong indices.
This happens because splice shrinks the array @copy, and after that, the original and copy arrays aren't aligned any more. You need yet another variable which holds the amount of elements spliced off, and decrease $sixindex by that amount at the next splice operation, otherwise the offset is outside the @copy array.
Adding some debug print statements shows the problem:
#!/usr/bin/perl use warnings; use strict; use Data::Dump; ######## my $aref = [1, 6, 2, 2, 7, 1, 6, 99, 99, 7]; my $flag = 0; my $i = 1; my $sixindex = 0; my @copy = @$aref; if (scalar(@$aref) >= 2) { foreach my $x (0..$#{$aref}) { print "pass $x\n"; dd $aref; dd \@copy; if (defined($aref->[$x])) { if ($aref->[$x] == 6) { $flag = 1; $sixindex = $x; next; } if ($flag) { unless ($aref->[$x] == 7) { $i++; next; } elsif ($aref->[$x] == 7 ) { print "splice $sixindex, ",($i+1),"\n"; splice(@copy, $sixindex, $i + 1); $flag = 0; $i = 1; $sixindex = 0; next; } } } } } dd \@copy; __END__ pass 0 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] pass 1 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] pass 2 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] pass 3 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] pass 4 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] splice 1, 4 pass 5 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 1, 6, 99, 99, 7] pass 6 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 1, 6, 99, 99, 7] pass 7 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 1, 6, 99, 99, 7] pass 8 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 1, 6, 99, 99, 7] pass 9 [1, 6, 2, 2, 7, 1, 6, 99, 99, 7] [1, 1, 6, 99, 99, 7] splice 6, 4 [1, 1, 6, 99, 99, 7]
The second splice at pass 9 has an offset of 6, but the last element of @copy is at index 5. Pass 4 spliced off 4 elements, so you want offset 2 here (6 - 4).
This does what you want:
#!/usr/bin/perl use warnings; use strict; use Data::Dump; ######## my $aref = [1, 6, 2, 2, 7, 1, 6, 99, 99, 7]; my $flag = 0; my $i = 1; my $sixindex = 0; my $spliced = 0; my @copy = @$aref; if (scalar(@$aref) >= 2) { foreach my $x (0..$#{$aref}) { print "pass $x\n"; dd $aref; dd \@copy; if (defined($aref->[$x])) { if ($aref->[$x] == 6) { $flag = 1; $sixindex = $x; next; } if ($flag) { unless ($aref->[$x] == 7) { $i++; next; } elsif ($aref->[$x] == 7 ) { print "splice ",$sixindex-$spliced, " ",($i+1 +),"\n"; splice(@copy, $sixindex-$spliced, $i + 1); $spliced += $i + 1; $flag = 0; $i = 1; $sixindex = 0; next; } } } } } dd \@copy;
All that indexing stuff is only necessary because you make a copy of the array and delete the ignored elements later. Is that a requirement of the homework? If not, you could drop all that index counting and track keeping stuff, and just push the elements not to be ignored onto @copy :
#!/usr/bin/perl use warnings; use strict; use Data::Dump; ######## my $aref = [1, 6, 2, 2, 7, 1, 6, 99, 99, 7]; my $flag = 0; my @copy; if (scalar(@$aref) >= 2) { foreach my $x (@$aref) { dd $aref; dd \@copy; if (defined($x)) { if ($x == 6) { $flag = 1; next; } if ($flag) { next unless $x == 7; $flag = 0; next; } print "push \@copy,$x\n"; push @copy, $x; } } } dd \@copy;
The only helper variable left now is $flag. But Perl has the ".." range operator which acts like a flip-flop, and as such has the $flag boolean built-in. Using that:
#!/usr/bin/perl use warnings; use strict; use Data::Dump; ######## my $aref = [1, 6, 2, 2, 7, 1, 6, 99, 99, 7]; my $flag = 0; my @copy; if (scalar(@$aref) >= 2) { foreach my $x (@$aref) { dd $aref; dd \@copy; if (defined($x)) { if ($x == 6 .. $x == 7) { next; } print "push \@copy,$x\n"; push @copy, $x; } } } dd \@copy;
Condense that a bit further, and you have tybalt89's solution.
In reply to Re: Ignore a range of numbers in a List
by shmem
in thread Ignore a range of numbers ina List
by pr33
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