http://qs321.pair.com?node_id=134831

ryan has asked for the wisdom of the Perl Monks concerning the following question:

I am using formatting to output some information, I was wishing to supress the display of all zero (0) values.

Setting the variables concerned to blank '' or undefing them only causes errors. 
format top =
User            Emails   Size (Kb)
============== ======== ===========
.
format DISPLAY =
@<<<<<<<<<<<<<   @####   @#####.##
$output[$i], $output[$i+1], $output[$i+2]/1024
.

[download]
Can it be done?

Thanks ... Ryan

Replies are listed 'Best First'.
Re: Supressing zero values in formatted reports
by robin (Chaplain) on Dec 28, 2001 at 15:41 UTC
    From the perlform manpage: 
           Picture fields that begin with ^ rather than @ are treated
       specially.  With a # field, the field is blanked out if
       the value is undefined.  For other field types, the caret
       enables a kind of fill mode.

    [download]
    So change your @#### to ^####, and make sure the values you want to suppress are undefined.

    The second problem is that using an undefined value when warnings are enabled will generate several warning messages. I suggest disabling warnings within the format, like this: 

    { no warnings;
format STDOUT =
@<<<<<<<<<<<<<   ^####   @#####.##
$output[$i], $output[$i+1], $output[$i+2]/1024
.
}

    [download]
[reply]
[d/l]
[select]
      hmm guess i should read more carefully next time ;-)

      thx
      fengor

      --
      "WHAT CAN THE HARVEST HOPE FOR IF NOT THE CARE OF THE REAPER MAN"
      -- Terry Pratchett, "Reaper Man"

[reply]
      That works, thanks for that, I must try to search more for the answers for these things. I did a lot of searching in the wrong places :)
[reply]
Re: Supressing zero values in formatted reports
by Fengor (Pilgrim) on Dec 28, 2001 at 14:04 UTC
    From the perfunc page of format: 
        format Something =
        Test: @<<<<<<<< @||||| @>>>>>
              $str,     $%,    '$' . int($num)
    .


    $str = "widget";
    $num = $cost/$quantity;
    $~ = 'Something';
    write;

    [download]
    so maybe u can do something like: 
    format top =
User            Emails   Size (Kb)
============== ======== ===========
.
format DISPLAY =
@<<<<<<<<<<<<<   @####   @#####.##
$temp[$i], $temp[$i+1], $temp[$i+2]
.

if ($output[$i]) {$temp[$i]=$output[$i]}
else {$temp[$i]==' '}

if ($output[$i+1]) {$temp[$i+1]=$output[$i+1]}
else {$temp[$i+1]==' '}

if ($output[$i+2]) {$temp[$i+2]=$output[$i+2]/1024}
else {$temp[$i+2]==' '}

    [download]
    hth
    fengor

    --
    "WHAT CAN THE HARVEST HOPE FOR IF NOT THE CARE OF THE REAPER MAN"
    -- Terry Pratchett, "Reaper Man"

[reply]
[d/l]
[select]
      Thanks, however that causes the same Argument " " isn't numeric in formline error that setting it to blank does.
[reply]
        Hmm this isn't an error. It's a warning.

        From perldiag: Argument "%s" isn't numeric%s

        (W) The indicated string was fed as an argument to an operator that expected a numeric value instead. If you're fortunate the message will identify which operator was so unfortunate.

        This means although the warning is displayed your program should run normally.

        hth
        fengor

        --
        "WHAT CAN THE HARVEST HOPE FOR IF NOT THE CARE OF THE REAPER MAN"
        -- Terry Pratchett, "Reaper Man"

[reply]

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