Re: Performing addition on hex value extracted from a string

in reply to Performing addition on hex value extracted from a string

Hopefully a more complete and self contained example for haukex explanation:

#!/usr/bin/env perl

use v5.10;
use strict;
use warnings;

use Math::BigInt;

use constant offset => Math::BigInt->new('0x500000000');

while (my $line1 = <DATA>) {
    # if addr 0x10000 written like 0x010000 then
    # 0x(?:[[:xdigit:]]{2})+)\b may validate memory address
    my ($addr) = $line1 =~ /addr:(0x[[:xdigit:]]+)\b/;

    #    print "addr is $addr\n";
    if (defined $addr) {
        my $new_addr = sprintf "0x%x", hex($addr) + offset;
        if ($line1 =~   s/ \baddr: \K $addr (?=\s+qospri:)
                        /$new_addr/x
        ) {
            print $line1;
        }
        else {
            print STDERR "unchanged\n";
            print $line1;
        }
    }
}

__DATA__
chn:req mon:orig cmd:SDP_CMD_WRSIZEDFULL tag:0x3b9aca01 addr:0xdf7780 
+qospri:0 len:0xf
[download]

Update: requirement for even number of digits removed thanks to explanation from AnamalousMonk.

Ron

Comment on Re: Performing addition on hex value extracted from a string Download Code

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Re^2: Performing addition on hex value extracted from a string by AnomalousMonk (Archbishop) on Feb 21, 2019 at 19:12 UTC
`my ($addr) = $line1 =~ /addr:(0x(?:[[:xdigit:]]{2})+)/;` If the hex value really is an address as `'addr'` suggests, is there any guarantee the hex digits will always be paired, i.e., always be an even number of digits? If they are not paired, won't the lack of a boundary assertion sometimes cause an incorrect value to be extracted from the string? `c:\@Work\Perl\monks>perl -wMstrict -le "my $line1 = 'addr:0xabcde'; my ($addr) = $line1 =~ /addr:(0x(?:[[:xdigit:]]{2})+)/; print qq{'$addr'}; " '0xabcd'` [download] Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]

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Re^2: Performing addition on hex value extracted from a string
by AnomalousMonk (Archbishop) on Feb 21, 2019 at 19:12 UTC

my ($addr) = $line1 =~ /addr:(0x(?:[[:xdigit:]]{2})+)/;

If the hex value really is an address as 'addr' suggests, is there any guarantee the hex digits will always be paired, i.e., always be an even number of digits? If they are not paired, won't the lack of a boundary assertion sometimes cause an incorrect value to be extracted from the string?

c:\@Work\Perl\monks>perl -wMstrict -le
"my $line1 = 'addr:0xabcde';
 my ($addr) = $line1 =~ /addr:(0x(?:[[:xdigit:]]{2})+)/;
 print qq{'$addr'};
"
'0xabcd'
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Give a man a fish: <%-{-{-{-<

[reply]
[d/l]
[select]

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