find which subgroups don't match in regex

[Shoryuken]

Hello gents, here's the thing been confusing me for a while:

$regex="(\w+)\s([0-9]+)";

$a="Tom 1990"; # it's a match
$b="Jack xyz"; # not a match, because of $2 doesn't match ... but
here's my question, exactly how to inform the users of this unmatched
subgroup? (i.e. $2 is the problem, $1 is fine, etc.)

For a regex matching, is there a way to find which subgroups don't
match?

thanks in advance.

 

[Ben Morrow]

Hello gents, here's the thing been confusing me for a while:

$regex="(\w+)\s([0-9]+)";

$a="Tom 1990"; # it's a match
$b="Jack xyz"; # not a match, because of $2 doesn't match ... but
here's my question, exactly how to inform the users of this unmatched
subgroup? (i.e. $2 is the problem, $1 is fine, etc.)

For a regex matching, is there a way to find which subgroups don't
match?

You can use /gc and \G to match one piece at a time, without losing your
place; something like

my @matches = qw/ \w+ \s [0-9]+ /;
my $string = 'Jack xyz';

for my $match (@matches) {
$string =~ /\G$match/gc
or print "$match failed at position " . pos $string;
}

Ben

 

[xhoster]

Hello gents, here's the thing been confusing me for a while:

$regex="(\w+)\s([0-9]+)";

$a="Tom 1990"; # it's a match
$b="Jack xyz"; # not a match, because of $2 doesn't match ... but
here's my question, exactly how to inform the users of this unmatched
subgroup? (i.e. $2 is the problem, $1 is fine, etc.)

For a regex matching, is there a way to find which subgroups don't
match?

There isn't a built-in way. You'd have to build it yourself, and that
will probably be non-trivial, as it would pretty much have to be an expert
system in your exact context, not just some standard Perl feature.

For example, whose "fault" is it that this doesn't match:

"1990 Tom" =~ /(\w+)\s(\d+)/;

Both subgroups will match individually, just not when put together.

Xho

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[Shoryuken]

Hello gents, here's the thing been confusing me for a while:

$regex="(\w+)\s([0-9]+)";

$a="Tom 1990"; # it's a match
$b="Jack xyz"; # not a match, because of $2 doesn't match ... but
here's my question, exactly how to inform the users of this unmatched
subgroup? (i.e. $2 is the problem, $1 is fine, etc.)

For a regex matching, is there a way to find which subgroups don't
match?

You can use /gc and \G to match one piece at a time, without losing your
place; something like

my @matches = qw/ \w+ \s [0-9]+ /;
my $string = 'Jack xyz';

for my $match (@matches) {
$string =~ /\G$match/gc
or print "$match failed at position " . pos $string;
}

Ben

This is a great idea, thanks!

And thanks the other guys for the good input, too!