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

hi there,

i am trying to get the printf function to print a variable. the issue is complex (for me) as the variable i am trying to print(f) contains strings and integers. i would like to print in a nice format. is this possible.... ? see my example code: 

my $pi = 3.14159;
printf "%11s %3d %5.1f\n", "Hello there", 123, $pi;  # this works fine
+!

$newarray="%11s %3d %5.1f\nHello there";
$newarray.=" 123 $pi";

printf $newarray;  # this doesn't work :-( as the printf above, any id
+eas?

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20050213 Janitored by Corion: Added formatting

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Re: printf and variables
by friedo (Prior) on Feb 13, 2005 at 21:03 UTC
    That doesn't work because printf requires two arguments, a format string and a list of variables to coerce into the format. If you say printf $newarray (a rather odd choice of variable name, BTW) then you're only sending one argument to printf. You can do what you want by simply doing: 

    my $format = '%11s %3d %5.1f\n';
printf $format, 'Hello there', 123, $pi;

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[d/l]
      friedo / zaxo thanks....... much appreciated
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Re: printf and variables
by Zaxo (Archbishop) on Feb 13, 2005 at 21:03 UTC

    That's an odd thing to do, but it will work if you seperate all the array elements with newlines and say, printf split /\n/, $newarray;.

    It will work better if you use a real array, 

    my @newarray = ('Hello there %3d %5.1f\n');
push @newarray, 123, $pi;
printf @newarray;

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    I absorbed the constant greeting into the format string.

    After Compline,
    Zaxo

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[d/l]
[select]

      This is close to how I quite often do this very thing:

      my $format = "Hello there %3d!";
my @data = (123);

if (defined $pi) # if we've calculated pi ...
{
  $format .= " %5.1f";
  push @data, $pi;
}

printf "$format\n", @data;

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      Very useful to be able to do this. The above example specifically doesn't seem too useful, but the overall idea is quite useful. At least to me.

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Re: printf and variables
by m-rau (Scribe) on Feb 13, 2005 at 21:12 UTC
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