Weird hash access problem

[tehjord]

Hi, im making some cheap chess game, but I got a very weird problem when accessing an hash using $1 following a regex match. The regex used works perfectly, but the problem is, when I try to access my hash table using the $1 var, it simply does not work. Ive tried first copying $1 to a temp var and then using that temp var to access my hash but with no success. Here is my code which should explain everything:

use strict;

my %h = (a1 => 1);

my $test = "a1 to a2";

if ($test =~ /([a-hA-H][1-8]\s*)to(\s*[a-hA-H][1-8])/)
{
    print "test work\n"; 
}

print $h{$1}; #print nothing
print $h{a1}; #print 1

print $1; #print "a1"

THX FOR THE REPLIES ! works !

[toolic]

Try this (Basic debugging checklist, Tip #3):

print ">>>$1<<<"; #print "a1"

You will see that there is a space after a1:

>>>a1 <<<

'a1 ' is not the same as 'a1' as a hash key.

You should also use warnings because it tells you which line is fishy.

See also: chess

[wind]

Change your regex, you're capturing the spacing:

if ($test =~ /([a-hA-H][1-8])\s*to\s*([a-hA-H][1-8])/) {

[kennethk]

$1 does not contain what you think it does. If you modify your code to wrap your output in a delimiter:

use strict;

my %h = (a1 => 1);

my $test = "a1 to a2";

if ($test =~ /([a-hA-H][1-8]\s*)to(\s*[a-hA-H][1-8])/)
{
    print "test work\n"; 
}

print "x$h{$1}x\n"; #print nothing
print "x$h{a1}x\n"; #print 1

print "x$1x\n"; #print "a1"

you get:

test work
xx
x1x
xa1 x

You are grabbing whitespace in addition to your square id. You'll get your expected result if you modify your regular expression to:

/([a-hA-H][1-8])\s*to\s*([a-hA-H][1-8])/

[ikegami]

print $1; #print "a1"

No, it prints "a1 ". Your parens are misplaces in your regex pattern.

... Too slow. But wow, 4 replies in a span that could be as little as 61 seconds!

[jfroebe]

The scope of "$1" with respect to the regular expression is within the if block IIRC. Who knows what "$1" is outside of if block. Btw, you forgot "use warnings;" after "use strict;"

[ikegami]

It's being used in the same block as the one in which it's set.

[jfroebe]

Interesting. I would have thought that the scope of what is in the if (...) would be only within the if (...) { } code block. The fact that it works doesn't mean the code should be written that way IMHO.