Tracking of number of elements in an array iterated?

Question

Is there any way that number of elements iterated in an for loop can be traced in perl: Like using special variables:

@arrayElements = (2,3,4,5,6,7,67);
foreach (@arrayElements) {
    # Do something
    # Want to know how may elements been iterated after 
    # some n number of elements processed without using another variable.
}

score 8 · Answer 1 · answered Apr 16 '13 at 17:07

8

Either just count as you go:

my $processed = 0;
foreach my $element (@array_elements) {
    ...
    ++$processed;
}

or iterate over the indexes instead:

foreach my $index (0..$#array_elements) {
    my $element = $array_elements[$index];
    ...
}

answered Apr 16 '13 at 17:07

ysth

96,171
6
121
214

FYI, my downvote was a mislick in the Android browser. Just noticed it, too late to alter. – Julian Fondren Apr 17 '13 at 02:52
1

You could also put the `++$processed;` in a [`continue`](http://perldoc.perl.org/functions/continue.html "perldoc -f continue") block. – Brad Gilbert Apr 17 '13 at 19:22

score 4 · Accepted Answer · answered Apr 16 '13 at 17:10

4

In perl5 v12 and later, you can use the each iterator:

while(my($index, $element) = each @array_elements) {
  ...;
}

However, the more portable solution is to iterate over the indices, and manually access the element, as shown by ysth.

In any case, the number of elements that were visited (including the current element) is $index + 1.

answered Apr 16 '13 at 17:10

amon

57,091
2
89
149

Thanks @amon ....each with arrays has an speciality like this ....Thats cool!!!!! – Srivatsa Jenni Apr 16 '13 at 17:18
1

If you do use the iterator, for safety, make sure it is set to the beginning before the loop with a void-context `keys @array_elements;` – ysth Apr 16 '13 at 17:21
1

If you do use this, you should include a `use 5.012;`, or `use 5.12.0` in your program. – Brad Gilbert Apr 17 '13 at 19:17

Futuregeek · Answer 3 · 2013-04-17T08:25:55.820

0

You may get the number of elements in an array as

    my $num = @arrayElements;
    print $num;

OR

   my $num = scalar (@arrayElements);
   print $num;

OR

   my $num = $#arrayElements + 1;
   print $num;

And for finding number of elements iterated, we can use the below code :

my $count = 0;  #initially set the count to 0
foreach my $index(@arrayElements)
{
  $count++;
}
print $count;

edited Apr 17 '13 at 08:25

answered Apr 17 '13 at 07:07

Futuregeek

1,900
3
26
51

Tracking of number of elements in an array iterated?

3 Answers3