Perl Problems with Digit Precision Changing on the Printf Statement

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

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Re: Perl Problems with Digit Precision Changing on the Printf Statement by davido (Cardinal) on Jun 24, 2004 at 15:39 UTC
The problem is that you're stringifying the number at the wrong point. If you print the number as a string (%s20), it will pad with whitespace. If you print the number as a number, it will pad with zeros. If you want 19 decimal places, you would use something like "%.19f". Try that and you'll see what I mean. The documentation for sprintf explains format strings as used by sprintf and printf. Also, for high-precision floating point, you may find it more reliable to use Math::BigInt. Dave	[reply]
Re: Perl Problems with Digit Precision Changing on the Printf Statement by tinita (Parson) on Jun 24, 2004 at 15:28 UTC
define "won't work". what do you expect, and what do you get with that code snippet? besides that, you might want to use the star : `printf STDOUT ("\n%s\n", $digitprecision, $value);` for that.	[reply] [d/l]
Re^2: Perl Problems with Digit Precision Changing on the Printf Statement by EchoAngel (Pilgrim) on Jun 24, 2004 at 15:35 UTC
i mean i want those two lines to output the same OUTPUT to screen. when i run `printf STDOUT ("\n%s\n", $digitprecision, $value);` [download] I get 'Use of in printf format not supported at example.pl line 10'	[reply] [d/l]
Re^3: Perl Problems with Digit Precision Changing on the Printf Statement by tinita (Parson) on Jun 24, 2004 at 15:40 UTC
oh, i'm getting the same output (v5.8.0 linux at the moment). what perl version are you using? regarding `%*s`: i don't know since which perl version it is allowed...	[reply] [d/l]
Re: Perl Problems with Digit Precision Changing on the Printf Statement by Roy Johnson (Monsignor) on Jun 24, 2004 at 15:55 UTC
It works for me. The second one has a trailing newline that the first doesn't have, of course. You could also interpolate $digitprecision right in the format string: `printf STDOUT ("\n%${digitprecision}s\n" , $value);` [download] Include the output you're getting from the two lines so we can see the problem. I do find it a little odd, talking about "digit precision" when you're telling printf that you're printing a string. We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply] [d/l]
Re^2: Perl Problems with Digit Precision Changing on the Printf Statement by EchoAngel (Pilgrim) on Jun 24, 2004 at 17:31 UTC
I want the output from `my $value = "0.03443762"; $digitprecision = 20; printf STDOUT ("\n%20s\n", $newvalue);` [download] I want the this printf statement to print exactly as it is `output 0.03443762` [download] so how do i program this using $digitprecision = 20; I need to control the number of spacing using a variable	[reply] [d/l] [select]
Re^3: Perl Problems with Digit Precision Changing on the Printf Statement by Roy Johnson (Monsignor) on Jun 24, 2004 at 17:42 UTC
Just like you did, or like I responded: `# You did this, and it works: printf STDOUT ("\n%" . $digitprecision . "s\n", $newvalue); # I suggested this, and it works, too: printf STDOUT ("\n%${digitprecision}s\n", $newvalue);` [download] We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply] [d/l]
Re^4: Perl Problems with Digit Precision Changing on the Printf Statement by EchoAngel (Pilgrim) on Jun 24, 2004 at 18:51 UTC
Re: Perl Problems with Digit Precision Changing on the Printf Statement by Fletch (Bishop) on Jun 24, 2004 at 15:40 UTC
You need to define "doesn't work" and state what results you expected. `freebie:~ 604> perl -le '$a="abc"x3;for $w (10, 15, 20) { printf "\|%-$ +{w}s\|\n", $a }' \|abcabcabc \| \|abcabcabc \| \|abcabcabc \|` [download]	[reply] [d/l]