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Number of elements in array

by Freezer (Sexton)
on Sep 24, 2012 at 13:35 UTC ( #995380=perlquestion: print w/ replies, xml ) Need Help??
Freezer has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

while(my @row_A_count_A_Ref_vs_Comp_B = $sth_Count_Ref_vs_Comp_B +->fetchrow_array()) {
I really want to know what the number of elements in  @row_A_count_A_Ref_vs_Comp_B is. I have tried the obvious, however I get strange numbers back. I think the problems lie in how the array is filled. Suggestion for lines on investigation welcomed.

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Re: Number of elements in array
by Anonymous Monk on Sep 24, 2012 at 13:43 UTC

    I have tried the obvious, however I get strange numbers back.

    Such as?

    Suggestion for lines on investigation welcomed.

    trace, Dumper, the basics :)

Re: Number of elements in array
by Corion (Pope) on Sep 24, 2012 at 13:48 UTC

    What is "the obvious", and what strange numbers did you get?

Re: Number of elements in array
by NetWallah (Abbot) on Sep 24, 2012 at 13:55 UTC
    If you want to get the number of rows in a database table, the most efficient way would be to let the database count them:
    ...prepare ("Select COUNT(*) FROM TABLE_OR_QUERY"); # TABLE_OR_QUERY can be another (SELECT...) statement
    Most databases will optimize queries, so you can do the count query, then do the data query as 2 separate queries.

                 I hope life isn't a big joke, because I don't get it.
                       -SNL

      This counts the number of rows. The OP was counting the number of columns.

      Of course, it's possible that the OP did actually want the number of rows...

      perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'
Re: Number of elements in array
by blue_cowdawg (Prior) on Sep 24, 2012 at 13:57 UTC
        Suggestion for lines on investigation welcomed

    OH Chilly Monk,
    If I want to know the number of elements in an array I'd try one of two things:

    # assume two arrays with a number of elements # @rray1 & @rray2 my $elements_1 = scalar @rray1; # or my $elements_2 = $#rray2 + 1;
    Either of the two will work.


    Peter L. Berghold -- Unix Professional
    Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

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