Perl - regular expression to match variable number of digits after string

kcleveland · 12-06-2011, 10:49 AM

I'm trying to parse a number out of the following string using perl (not my forte, as you can see):

Code:

Contact: 5005 <sip:5005@127.0.0.1:5062>

I need to get the "5005" part that comes directly after "Contact:"

5005 will be a different number each time (and can be any length between 4 digits and 12 digits), so I can't rely on matching to a constant.

I've tried several variations of this (For some reason, I'm terrible with regular expressions, and always have been, which is why I must ask for help on this one):

Code:

$SIPuserID=~s/\Contact:[^\n]*\n/s;

I have tried for hours with no success - can anyone help me out here?

Thanks!

jhwilliams · 12-06-2011, 11:02 AM

This prints out 5005:

Code:

#!/usr/bin/perl
$SIPuserID = "Contact: 5005 <sip:5005@127.0.0.1:5062>";
$SIPuserID =~ s/^Contact: ([0-9]*) .*/$1/;
print "$SIPuserID\n"

The ^ means "line starts with"

() means "save whatever you find here" (so we can reference it with $1.)
[0-9]* matches a sequence of 0-n digits.
.* matches whatever else may come after.

Regular expressions are extremely useful, I use them constantly. If you're not feeling excellent at them, I would highly recommend setting aside an afternoon to buff up.

kcleveland · 12-06-2011, 11:27 AM

Thanks jhwilliams!

I will take your advice - this Saturday afternoon has officially become "Regex Saturday".

Thanks for the code, it works perfectly.

jhwilliams · 12-06-2011, 11:30 AM

Quote:

Originally Posted by kcleveland

Thanks jhwilliams!

I will take your advice - this Saturday afternoon has officially become "Regex Saturday".

Thanks for the code, it works perfectly.

Excellent! I'm having another AWK Saturday, myself.

devUnix · 12-08-2011, 04:46 AM

Note: I have repeated the variable to show to examples:

Source File:
$ cat oye.pl

Code:

#! /usr/bin/perl 
$SIPuserID = "Contact: 5005 <sip:5005@127.0.0.1:5062>";
if($SIPuserID =~ /Contact: ([0-9]+)\s/){ print $1; print "\n";}

$SIPuserID = "Contact: 50058788770 <sip:5005@127.0.0.1:5062>";
if($SIPuserID =~ /Contact: ([0-9]+)\s/){ print $1; print "\n";}

A Sample Run:
$ ./oye.pl

Code:

5005
50058788770