perl matching *-length strs

towlie · 07-21-2004, 06:09 PM

I'm having problems matching a variable length
string in perl using m// and parens.

I still want perl to be greedy, I just want it
to pick up every char along the way. The code
below just gives me the last char, but I would
like to get all of them between each letter.

Also, if there are any 2 consecutive letters
without digits between them, I want the match
to give me the empty string.

Anyone know what I should change my regex to?

Thanks for your help!

Code:

#!/usr/bin/perl


# in first 2 examples would like to get the entire strings
# between each of the letters
$str= 'a1b22c333d4444e55555f';

$str =~ m/[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*/g;

print "1:$1   2:$2   3:$3   4:$4 \n\n";
	#desired output is '1:1   2:22   3:333   4:4444 ....'




$str= 'a1b23c456d7890e12345f';

$str =~ m/[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*/g;

print "1:$1   2:$2   3:$3   4:$4 \n\n";
		#desired output is '1:1   2:23   3:456   4:7890 ....'





# also, would like to return empty string if
# any 2 letters have no separation ('abc' in this example)
$str= 'abc456d7890e12345f';

$str =~ m/[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*[a-f]([^a-f])*/g;

print "1:$1   2:$2   3:$3   4:$4 \n\n";
	#desired output is '1:   2:   3:456   4:7890 ....'

Here is the output I get:

Code:

1:1   2:2   3:3   4:4

1:1   2:3   3:6   4:0


1:   2:   3:6   4:0

Here is what I want to get:

Code:

1:1   2:22   3:333   4:4444

1:1   2:23   3:456   4:7890


1:   2:   3:456   4:7890

Lansing_Banda · 07-21-2004, 06:43 PM

If all your strings are that lenght:

Code:

m/\D(\d+)\D(\d+)\D(\d+)\D(\d+)\D(\d+)\D/g

Will fix your first two problems. As for the third, I can't think right now because I am at work, I will edit this later if I get a chance.

towlie · 07-21-2004, 08:13 PM

Thanks Lansing_Banda!

your code showed me what my mistake was.

I needed to put the asterik inside the parentheses

Seems obvious to me now, what was I thinking?

Here is the revised code:

Code:

#!/usr/bin/perl

# revised this code to put the asterik inside the paren

$str= 'a1b22c333d4444e55555f';
$str =~ m/[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)/g;
print "1:$1   2:$2   3:$3   4:$4 \n\n";


$str= 'a1b23c456d7890e12345f';
$str =~ m/[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)/g;
print "1:$1   2:$2   3:$3   4:$4 \n\n";

$str= 'abc456d7890e12345f';
$str =~ m/[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)[a-f]([^a-f]*)/g;
print "1:$1   2:$2   3:$3   4:$4 \n\n";

and the correct output:

Code:

1:1   2:22   3:333   4:4444 

1:1   2:23   3:456   4:7890 

1:   2:   3:456   4:7890