Illegal hexadecimal digit error

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

Does anyone know why I'm getting this error:

Illegal hexadecimal digit '
' ignored at G:\Beta\Trap_Tool\hex.pl line 9.
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from the following code:

#!/usr/bin/perl

use warnings;
use strict;

my $num = "0x10000000";
for (0..5) {
    
    my $dec_num = sprintf("%d", hex("$num"));
    print "DEC: $dec_num\n";
    $dec_num ++;

    my $hex_num = sprintf "0x" . "%x\n", $dec_num; 
    print "HEX: $hex_num\n";
    $num = "$hex_num";
}
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Comment on Illegal hexadecimal digit error Select or Download Code

Replies are listed 'Best First'.
Re: Illegal hexadecimal digit error by Abigail-II (Bishop) on Jul 07, 2003 at 14:40 UTC
The `sprintf` that assigns to `$hex_num` contains a newline. Newlines aren't hex numbers, just as the warning says. Abigail	[reply]
(jeffa) Re: Illegal hexadecimal digit error by jeffa (Bishop) on Jul 07, 2003 at 14:40 UTC
That's a warning, not an error ... it results from trying to convert a hex 'number' which has a newline in it. Remove the newline: `my $hex_num = '0x' . sprintf('%x', $dec_num);` [download] Also, don't use quotes when you copy `$hex_num` to `$num` at the end of the loop (it doesn't make a difference here, but it is a bad habit to get into). jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l]
Re: Illegal hexadecimal digit error by tadman (Prior) on Jul 07, 2003 at 17:43 UTC
Or even better, put it all in `sprintf`: `my $hex_num = sprintf("0x%x", $dec_num);`	[reply] [d/l]
Re: Illegal hexadecimal digit error by dws (Chancellor) on Jul 07, 2003 at 16:37 UTC
Note that you start getting this warning on the second trip through the loop. The first time through, `$num` gets a newline tacked onto the end of it. Remove the \n in the second `sprintf`, and the problem goes away.	[reply] [d/l] [select]