If the second variable is always just 2 numbers seperated by a "." I'd suggest doing it this way:

Not a regex thou...

Update at -2: Yes! It's not a regex. But: Why should one use a regex here where a simple string comparison will do?

Could those downvoters please comment what they think is wrong with my solution except that I don't break a fly on the wheel.

Very clever, adding a dot after the variables to make sure you do not get a false positive in case of partial matches!

++ wel deserved.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

If you use a regex, you're going to have to quotemeta one of the strings because '.' is a meta (regex command) character.

If you use substr, you'll have problems if the length of the part you are trying to match can vary. Ie. Could the strings be '13.2.3' & '13.2' for example.

Using index will allow you to avoid both these problems. You simple want to know if the shorter string matches the longer string at position 0:

$var1 = '1.1.2'; 
$var2 = '1.1'; 
if( index( $var1, $var2 ) == 0 ) { 
    print "matches" 
} else { 
    print "Doesn't match" 
}
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This will never match and is completly wrong as you mixed up $var1 and $var2.

It should be

index( $var2, $var1 ) == 0

but this will still be wrong because

$var2='1.11.2';
$var1='1.1';
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would give you a false match

---

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

This will never match and is completly wrong as you mixed up $var1 and $var2.

Um, no.

C:\parrot>p1
[0] Perl> $var1 = '1.1.2'; $var2 = '1.1'; 
if( index( $var1, $var2 ) == 0 ) { print "matches" } 
else { print "Doesn't match" };;
matches

[0] Perl> $var1 = '1.1.2'; $var2 = '1.1'; 
if( index( $var2, $var1 ) == 0 ) { print "matches" } 
else { print "Doesn't match" };;
Doesn't match
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but this will still be wrong because

$var2='1.11.2';
$var1='1.1';
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would give you a false match

That's a good catch though. It's also easily fixed:

[0] Perl> $var1 = '1.11.2'; $var2 = '1.1'; 
if( index( $var1, "$var2." ) == 0 ) { print "matches" } 
else { print "Doesn't match" };;
Doesn't match
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---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

use strict;
use warnings;

my @dotted_stuff
    = (
       q(),
       '1.A',
       '12.1',
       '1.9',
       '01.9',
       '1.9.1',
       '1.9.2.1',
       '12.1.1',
       '12.13',
   );

for my $va (@dotted_stuff) {
    for my $vb (@dotted_stuff) {
        printf qq(%-7s and %-7s => ), $va, $vb;
        if ($va =~ m{ \A (\d+) \. (\d+) }xms) {
            my ($a1, $a2) = ($1, $2);
            if ($vb =~ m{ \A (\d+) \. (\d+) }xms) {
                my ($b1, $b2) = ($1, $2);
                if ($a1 == $b1 and $a2 == $b2) {
                    print "MATCH!\n";
                    next;
                }
            }
        }
        print "no match.\n";
    }
}
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If your second variable is always 3 characters and the first is always at least three characters, then it's not too hard, you could see if a substring of var1 eq var2. Or even the following works for me

if ($var1 =~ /^$var2/) {
  print "matched";
}
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Or you could do character by character comparisons. I'm sure in this case there are many ways to do it, though it would get complicated if you wanted to do a compare where $var1 used periods and $var2 used underscores or something.

UPDATE: 20070522 11:01 localtime > ++ to BrowserUK for index

UPDATE: 20070522 11:57 localtime > got a pm (thought it was a reply) and can't remember who sent it now, but props to the monk in question for reminding me to anchor the regex with ^

if( substr($v1, 0, 2) eq substr($v2, 0, 2) )
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if( (substr($v1, 0, 3) eq substr($v2, 0, 3) ) && 
    substr($v1, 1 ,1) eq '.' && substr($v2, 1 ,1) eq '.' )
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if( substr($v1, 0, 3) eq substr($v2, 0, 3) )
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