/^From:.*?([\w.-]+@[\w.-]+)/

[April]

found this re which claimed to match an email address:

/^From:.*?([\w.-]+@[\w.-]+)/

not sure I fully understand it, any help would be highly appreciated!

-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.

 

[Tim Greer]

found this re which claimed to match an email address:

/^From:.*?([\w.-]+@[\w.-]+)/

not sure I fully understand it, any help would be highly appreciated!

-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.

^ start of string.
From: Start of string that starts with From:
..*? zero or more characters (. is any character) non greedy (?)
anything in (...) is captured.
[ ] is a character class of \w (any word character a-z and underscores
_) or a dash (hyphen)
[...]+ wher e+ is one or more of the characters in the []
@ speaks for itself, though it should be \@, I'm sure (escaped).
Another char class, with one or more characters.

Unfortunately, that regular expression isn't very good. Not that a
regex is able to always accurately tell if it looks acceptable (and
certainly it can't know it's a real address), that above fails to do
some reasonable checks. After all, someone could put it as From: -@-
and it would be seen as valid... and so on. I'd recommend using a
different script or regular expression if you plan to use that script.

 

[Jürgen Exner]

found this re which claimed to match an email address:

Well, it might, for some. And it will match many non-email addresses and
will fail to match many actual addresses, too.

/^From:.*?([\w.-]+@[\w.-]+)/

not sure I fully understand it, any help would be highly appreciated!

It is a very(!) poor attempt. See 'perldoc -q valid'
"How do I check a valid mail address?"
for a discussion of the problems and more appropriate options.

jue

 

[Tad J McClellan]

found this re which claimed to match an email address:

/^From:.*?([\w.-]+@[\w.-]+)/

not sure I fully understand it, any help would be highly appreciated!

-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.

hyphen here means a hyphen character, ie. it is not a metacharacter.

[ ] is a character class of \w (any word character a-z and underscores
_)

\w also includes the digit characters.

or a dash (hyphen)

or a dot character.

@ speaks for itself, though it should be \@, I'm sure (escaped).

Why are you sure?

It does not need to be escaped, so you must misunderstand something...

Unfortunately, that regular expression isn't very good.

That is for sure.

 

[Tim Greer]

found this re which claimed to match an email address:

/^From:.*?([\w.-]+@[\w.-]+)/

not sure I fully understand it, any help would be highly
appreciated!

-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.

hyphen here means a hyphen character, ie. it is not a metacharacter.

[ ] is a character class of \w (any word character a-z and
[ underscores
_)

\w also includes the digit characters.

or a dash (hyphen)

or a dot character.

@ speaks for itself, though it should be \@, I'm sure (escaped).

Why are you sure?

It does not need to be escaped, so you must misunderstand something...

I don't know what I was thinking earlier. Thanks for pointing out those
flaws in my response.

 

[April]

April wrote:
found this re which claimed to match an email address:
/^From:.*?([\w.-]+@[\w.-]+)/
not sure I fully understand it, any help would be highly
appreciated!
-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.

hyphen here means a hyphen character, ie. it is not a metacharacter.

[ ] is a character class of \w (any word character a-z and
[ underscores
_)

\w also includes the digit characters.

or a dot character.

Why are you sure?

It does not need to be escaped, so you must misunderstand something...

I don't know what I was thinking earlier.  Thanks for pointing out those
flaws in my response.

--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!- Hide quoted text -

- Show quoted text -

Thanks Tim, Tad and Jue .. now it's much clear to me! One thing left
is whether .*? simply means anything appears before (...)? April

 

[Jürgen Exner]

April wrote:

/^From:.*?([\w.-]+@[\w.-]+)/

--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!- Hide quoted text -

[Please do not quote signatures]

Is this line meant to mean anything?

Thanks Tim, Tad and Jue .. now it's much clear to me! One thing left
is whether .*? simply means anything appears before (...)? April

<quoted from Tim>
..*? zero or more characters (. is any character) non greedy (?)
</quote>
:
Why don't you go and check 'perldoc perlre'? There you will find
. Match any character (except newline)
* Match 0 or more times
And the meaning of ? is explained two paragraphs down from there.

jue

 

[April]

April wrote:
/^From:.*?([\w.-]+@[\w.-]+)/
--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!- Hide quoted text -

[Please do not quote signatures]

Is this line meant to mean anything?

Thanks Tim, Tad and Jue .. now it's much clear to me!  One thing left
is whether .*? simply means anything appears before (...)?  April

<quoted from Tim>
.*? zero or more characters (. is any character) non greedy (?)
</quote>
:
Why don't you go and check 'perldoc perlre'? There you will find
        .   Match any character (except newline)
        *      Match 0 or more times
And the meaning of ? is explained two paragraphs down from there.

jue

not sure what viewer you are using, I'm using Google group and what
you gets is the default.

Also, no one learns a language by reading docs alone I guess .. I
appreciate your input when you care, otherwise you may choose to skip
please.

 

[April]

April wrote:
found this re which claimed to match an email address:
/^From:.*?([\w.-]+@[\w.-]+)/
not sure I fully understand it, any help would be highly
appreciated!
-- I especially having issues with the ".*?" part and also could not
find the meaning of "-" here.
hyphen here means a hyphen character, ie. it is not a metacharacter.
[ ] is a character class of \w (any word character a-z and
[ underscores
_)
\w also includes the digit characters.
or a dash (hyphen)
or a dot character.
@ speaks for itself, though it should be \@, I'm sure (escaped).
Why are you sure?
It does not need to be escaped, so you must misunderstand something....

I don't know what I was thinking earlier.  Thanks for pointing out those
flaws in my response.

--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!- Hide quoted text -

- Show quoted text -

Thanks Tim, Tad and Jue .. now it's much clear to me!  One thing left
is whether .*? simply means anything appears before (...)?  April- Hidequoted text -

- Show quoted text -

The reason I wasn't sure is that the following cannot be picked up by
an if test:

From (e-mail address removed) Tue Apr 24 11:02:41 2002

if test: elsif ($header && /^From:.*?([\w.-]+@[\w.-]+)/)

I modified From: to From in the above and also checked still in the
header secton.

In fact this is from the bayview website, Exercise "Analyze Mail
Folder", solution and auxilary files, but seems the solution is not
working for this part.

 

[Tim Greer]

if test:  elsif ($header && ^From:.*?([\w.-]+@[\w.-]+))

The above isn't showing any delimiters for me. Anyway, the From in your
example doesn't have a colon ) following it in the actual email
"from" line you posted. Where/what is $_ coming from for your check?
If $_ isn't what you want to check against, you might want $variable
=~ /m/. Anyway, try chaning it to /^From:?.*?([\w.-]+@[\w.-]+)/ :?
makes ":" optional in the regex match.

Also, do you want to capture the address? If not, you don't need to use
() in the regex. Again, I'd suggest a better check, especially if you
want to ensure it makes some attempt to verify it's at least a
legitimate _looking_ email address, but if you're not doing that, then
I suppose thw above should work for capturing most.

 

[Jürgen Exner]

[Please do not quote signatures]

- Show quoted text -

Is this line meant to mean anything?

not sure what viewer you are using,

I am not using any viewer. As you can easily see in the headers
currently I am using Forte Agent as my newsreader.

I'm using Google group and what

If you prefer a crude web page interface lacking any features and having
poor performance then of course that's your choice.

you gets is the default.

It has been customary for the past 25+ years to trim quotes to those
parts that are relevant to your reply. If Google Groups doesn't allow
you to do that then this is one more reason to avoid it.

Also I can only guess that your comment was related to those parts that
I quoted above and not to those that I snipped, because you didn't
bother to remove those that were irrelevant to your reply.

Also, no one learns a language by reading docs alone I guess .. I
appreciate your input when you care, otherwise you may choose to skip
please.

http://www.catb.org/~esr/faqs/smart-questions.html, in particular
http://www.catb.org/~esr/faqs/smart-questions.html#examples

You didn't show any indication about if or what you tried already to
answer the question yourself and neither what your underlying goals
where. This leaves the door wide open to all kinds of guesses including
but not limited to someone is too lazy to read TFM for himself, someone
is fishing for free lunch, someone did read TFM but didn't understand it
(too bad he didn't say which parts he has trouble with), someone didn't
know where to find TFM, ...

The case of "I am learning the language and just got stuck at this
specific spot and need a little help with it" unfortunately is the least
common case and therefore typically not the default assumption when all
indications for background and motivation are missing.

A suggestion:
If you want to learn about REs, then you could have sad so easily.
'I am learning REs and found this example: /^From:.*?([\w.-]+@[\w.-]+)/
Although I checked 'perldoc perlre' I still don't understand the '.*?'.
Could someone explain, please?'

This is very different from your question. Now people know what you are
after (so there is no need to go off on irrelevant tangents like the FAQ
answer on validating email addresses), what you tried already (so there
is no need to repeat that), and they know exactly where you got stuck
(so the answer can be specific and targeted).

jue

 

[Jürgen Exner]

The reason I wasn't sure is that the following cannot be picked up by
an if test:

From (e-mail address removed) Tue Apr 24 11:02:41 2002

if test: elsif ($header && /^From:.*?([\w.-]+@[\w.-]+)/)

I modified From: to From in the above

Well, the RE is explicitely asking for that colon. If it doesn't exist
in the text, then the RE won't match.

and also checked still in the header secton.

No idea what you mean by that sentence.

jue

 

[Tad J McClellan]

Also, no one learns a language by reading docs alone I guess ..

Also, no one learns a language by posting every question that
occurs to them to Usenet without even trying to find the answer
themselves first.

You are abusing our newsgroup. This does not endear you to us...

you may choose to skip
please.

Your choice appears to continue to do what is seen as rude here.

My choice is to auto-delete unread every post you make in the future. [1]

So long!




[1] Which is no big deal as there are lots of other people who can
read the docs to you. If however, dozens of others do the same,
then you eventually get less and less help here. Your choice.

 

[April]

The reason I wasn't sure is that the following cannot be picked up by
an if test:

   From (e-mail address removed) Tue Apr 24 11:02:41 2002

if test:  elsif ($header && /^From:.*?([\w.-]+@[\w.-]+)/)

I modified From: to From in the above

Well, the RE is explicitely asking for that colon. If it doesn't exist
in the text, then the RE won't match.

I did say when the : moved it still won't match ...

No idea what you mean by that sentence.

as && requires the matching needs to be done in the header ($header)
section ..

 

[April]

If you prefer a crude web page interface lacking any features and having
poor performance then of course that's your choice.


It has been customary for the past 25+ years to trim quotes to those
parts that are relevant to your reply. If Google Groups doesn't allow
you to do that then this is one more reason to avoid it.

Also I can only guess that your comment was related to those parts that
I quoted above and not to those that I snipped, because you didn't
bother to remove those that were irrelevant to your reply.

I applogize but am suprised people feel so strongly about the posting
style ... I always think posting with the history will provide
neccessary backgroud for anyone with convenience to respond, for
people familiar with the thread, skip the unneccessry part and get to
the point; for those unfamiliar, then have the background right
there ...

However, if that's what expected, I can adapt it ...

http://www.catb.org/~esr/faqs/smart-questions.html, in particularhttp://www.catb.org/~esr/faqs/smart-questions.html#examples

You didn't show any indication about if or what you tried already to
answer the question yourself and neither what your underlying goals
where. This leaves the door wide open to all kinds of guesses including
but not limited to someone is too lazy to read TFM for himself, someone
is fishing for free lunch, someone did read TFM but didn't understand it
(too bad he didn't say which parts he has trouble with), someone didn't
know where to find TFM, ...

the issue with TEM or other general doc is that they say so many
things the ways should be, however, they won't tell you whether and
how it applies to a particular case .. as a new leaner, what I need is
a confirmation that it applies here and in this way.

the other part I also have issues is to identfy things that are
specific applications of certain functions or statements, or whatever
you name it.

The case of  "I am learning the language and just got stuck at this
specific spot and need a little help with it" unfortunately is the least
common case and therefore typically not the default assumption when all
indications for background and motivation are missing.

A suggestion:
If you want to learn about REs, then you could have sad so easily.
'I am learning REs and found this example: /^From:.*?([\w.-]+@[\w.-]+)/
Although I checked 'perldoc perlre' I still don't understand the '.*?'.
Could someone explain, please?'

I don't know what you mean here, it seems to me based on my initial
question, anyone would figure out I'm new to Perl.

 

[April]

if test:  elsif ($header && ^From:.*?([\w.-]+@[\w.-]+))

The above isn't showing any delimiters for me.  Anyway, the From in your
example doesn't have a colon ) following it in the actual email
"from" line you posted.  Where/what is $_ coming from for your check?
If $_ isn't what you want to check against, you might want $variable
=~ /m/.  Anyway, try chaning it to  /^From:?.*?([\w.-]+@[\w.-]+)/  :?
makes ":" optional in the regex match.

Also, do you want to capture the address?  If not, you don't need to use
() in the regex.  Again, I'd suggest a better check, especially if you
want to ensure it makes some attempt to verify it's at least a
legitimate _looking_ email address, but if you're not doing that, then
I suppose thw above should work for capturing most.
--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!

Thanks Tim .. moved the test to the beginning of the script and either
removing the : or escaping it will be able to capture the email
addresses .. so it's a logic problem somewhere in the solution
provided, and I'll be working on that find it out. Really appreciate
your help and patience. April

 

[April]

if test:  elsif ($header && ^From:.*?([\w.-]+@[\w.-]+))

The above isn't showing any delimiters for me.  Anyway, the From in your
example doesn't have a colon ) following it in the actual email
"from" line you posted.  Where/what is $_ coming from for your check?
If $_ isn't what you want to check against, you might want $variable
=~ /m/.  Anyway, try chaning it to  /^From:?.*?([\w.-]+@[\w.-]+)/ :?
makes ":" optional in the regex match.

Also, do you want to capture the address?  If not, you don't need to use
() in the regex.  Again, I'd suggest a better check, especially if you
want to ensure it makes some attempt to verify it's at least a
legitimate _looking_ email address, but if you're not doing that, then
I suppose thw above should work for capturing most.
--
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
Shared Hosting, Reseller Hosting, Dedicated & Semi-Dedicated servers
and Custom Hosting.  24/7 support, 30 day guarantee, secure servers.
Industry's most experienced staff! -- Web Hosting With Muscle!

Thanks Tim .. moved the test to the beginning of the script and either
removing the : or escaping it will be able to capture the email
addresses .. so it's a logic problem somewhere in the solution
provided, and I'll be working on that find it out.  Really appreciate
your help and patience.  April- Hide quoted text -

- Show quoted text -

just an update .. after moving the specifc if loop up to be part of
the envelope check, now the errors in the provided "solution" fixed
and the script works as expected. Again, thanks everyone! - April

 

[Scott Bryce]

if test: elsif ($header && /^From:.*?([\w.-]+@[\w.-]+)/)

as && requires the matching needs to be done in the header ($header)

No. The $header && requires only that whatever value is stored in
$header evaluates to TRUE, which it would not do if it had no value at
all. It is probably a test to see whether $header contains a non-null value.

If you wanted to require that the matching be done to the value stored
in $header, you would write that as

elsif ($header =~ /^From:.*?([\w.-]+@[\w.-]+)/)

 

[Scott Bryce]

I applogize but am suprised people feel so strongly about the posting
style

The regulars here expect a certain posting style because it communicates
effectively in this medium.

... I always think posting with the history will provide neccessary
backgroud for anyone with convenience to respond, for people familiar
with the thread, skip the unneccessry part and get to the point; for
those unfamiliar, then have the background right there ...

What the regulars expect is that you will quote enough to provide
necessary background, and that YOU will skip the unnecessary parts by
trimming them from your post.

the issue with TFM or other general doc is that they say so many
things the ways should be, however, they won't tell you whether and
how it applies to a particular case .. as a new leaner, what I need
is a confirmation that it applies here and in this way.

Questions of that type should be fair game here.

the other part I also have issues is to identfy things that are
specific applications of certain functions or statements, or whatever
you name it.

Questions of that type should also be fair game here.

I don't know what you mean here, it seems to me based on my initial
question, anyone would figure out I'm new to Perl.

We know that you are new to Perl. What people want to see is some
indication that you are putting out some effort yourself, and that you
don't expect us to spoon feed it to you. If the answer to your question
is in the docs, hopefully you have made some effort to find the answer
there.

Have you read the posting guidelines that are posted here twice weekly?
They will help you ask your questions in a way that will make it easier
for people here to answer you.

 

[April]

if test:  elsif ($header && /^From:.*?([\w.-]+@[\w.-]+)/)

as && requires the matching needs to be done in the header ($header)

No. The $header && requires only that whatever value is stored in
$header evaluates to TRUE, which it would not do if it had no value at
all. It is probably a test to see whether $header contains a non-null value.

what I meant was as $header also needs to be evaluated true (&&), so
this test must be done in the header section which is what $header
stands for.