Re^3: Use of uninitialized value when using regex

[liverpole]

Hi Erez,

In scalar context:

my $build = ($vdata=~/=(\d+)$/);

you're correct; you will get 0 or 1.  But in list context:

(my $build) = ($vdata=~/=(\d+)$/);

you will get the captured values.  For example:

use strict;
use warnings;

my $text = "The quick brown fox jumps over the lazy dog";
my ($h, $i, $j) = $text =~ /(\S*h\S*).*?(\S*i\S*).*?(\S*j\S*)/;
print "$h, $i, $j\n";

__END__
Output:
The, quick, jumps

Hi roboticus,

I, too, thought this a simple case of not matching the newline.  However, I can't explain why I'm getting the following:

use strict;
use warnings;

# my $dir1 = 'Z:\My Documents\Workspace';
# my $versionFile = "$dir1\\version.txt";

# open (VFILE, $versionFile)|| die $!;
# my $vdata= <VFILE>;
# close (VFILE);

try_this("Version=2010-09-01_17-29-04 Build=26");
try_this("Version=2010-09-01_17-29-04 Build=26\n");
try_this("Version=2010-09-01_17-29-04 Build=26\n\n");


sub try_this {
    my ($vdata) = @_;
    print "=" x 69, "\n";
    print  "Str:  [$vdata]\n";
    printf "Asc:  %s\n\n", join ' ', map { ord $_ } split //, $vdata;

    (my $build) = ($vdata=~/=(\d+)$/);
    print "Build = [$build]\n\n";#this is the problem line
}


__END__
Output:
=====================================================================
Str:  [Version=2010-09-01_17-29-04 Build=26]
Asc:  86 101 114 115 105 111 110 61 50 48 49 48 45 48 57 45 48 49 95
 49 55 45 50 57 45 48 52 32 66 117 105 108 100 61 50 54

Build = [26]

=====================================================================
Str:  [Version=2010-09-01_17-29-04 Build=26
]
Asc:  86 101 114 115 105 111 110 61 50 48 49 48 45 48 57 45 48 49 95
 49 55 45 50 57 45 48 52 32 66 117 105 108 100 61 50 54 10

Build = [26]

=====================================================================
Str:  [Version=2010-09-01_17-29-04 Build=26

]
Asc:  86 101 114 115 105 111 110 61 50 48 49 48 45 48 57 45 48 49 95
 49 55 45 50 57 45 48 52 32 66 117 105 108 100 61 50 54 10 10

Use of uninitialized value $build in concatenation (.) or string at
 D:\Documents and Settings\jonorton\a.pl line 25.
Build = []

The first string (no newlines) matches as expected, and the third (2 newlines) fails, also as expected.  But the second (1 newline) matches, despite the newline at the end.  I'm not sure what to make of that.

This is on perl v5.10.0 for MSWin32-x86-multi-thread (Windows xp), binary build 1004 from ActiveState.