473,746 Members | 2,701 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Need help in forming a regular expression using regex_replace

Hello,

I am relatively new to the world of regex and require some help in
forming a regular expression to achieve the following:

I have an input stream similar to:

Slot: slot1
Description: this is a description
Slot: slot2
Description: this is the second description
Attribute1: atrra
Attribute2: attrb
Slot: slot3
Description: this is the third description
Attribute1: atrrc
Attribute2: attrd

I have to pick all the values for "Slot" and corresponding
"Attribute2 ". If there is no "Attribute2 " for a "Slot", I need to skip
that Slot.

I arrived at a regular exp similar to:
"^Slot:\\s+(.*? )\\s+Descriptio n:\\s+.*?\\s+At tribute1:\\s+.* ?\\s+Attribute2 :\\s+(.*?)\\s+. *?$"
but no luck. For the above example, this gives me "slot1 and attrd",
wheras I was expecting slot2, attrb and slot3, attrd.

Any thoughts on this is highly appreciated.

Thanks in advance!

Regards,
Deepak

Jul 11 '06 #1
6 2234
<de************ *@yahoo.co.inwr ote:
I am relatively new to the world of regex and require some help in
forming a regular expression...
This has absolutely nothing to do with C++. Ask this in a group
that deals more with regexes, like a Gnu utilities group, or
even a perl group:

gnu.utils.help
comp.lang.perl. misc

Also be aware that many programs that use regexes use non-standard
extensions. What program are you using your regexes with? Ask in
a group suitable for that program. Or call it's vendor on the phone.
Or visit the program's web site. Or read a book or manual on the
program. Or google for info on the program.

--
Cheers,
Robbie Hatley
East Tustin, CA, USA
lone wolf intj at pac bell dot net
(put "[usenet]" in subject to bypass spam filter)
http://home.pacbell.net/earnur/
Jul 11 '06 #2

Robbie Hatley wrote:
<de************ *@yahoo.co.inwr ote:
I am relatively new to the world of regex and require some help in
forming a regular expression...

This has absolutely nothing to do with C++. Ask this in a group
that deals more with regexes, like a Gnu utilities group, or
even a perl group:

gnu.utils.help
comp.lang.perl. misc

Also be aware that many programs that use regexes use non-standard
extensions. What program are you using your regexes with? Ask in
a group suitable for that program. Or call it's vendor on the phone.
Or visit the program's web site. Or read a book or manual on the
program. Or google for info on the program.
Not so! This group's stated subject matter is that which is related to
"the C++ language definition as determined by the ISO/ANSI C++ Standard
document, and by planned extensions and adjustments." In fact, TR1 (a
planned extension to the standard library) has a regex component.

Cheers! --M

Jul 11 '06 #3
de************* @yahoo.co.in wrote:
I am relatively new to the world of regex and require some help in
forming a regular expression to achieve the following:

I have an input stream similar to:

Slot: slot1
Description: this is a description
Slot: slot2
Description: this is the second description
Attribute1: atrra
Attribute2: attrb
Slot: slot3
Description: this is the third description
Attribute1: atrrc
Attribute2: attrd

I have to pick all the values for "Slot" and corresponding
"Attribute2 ". If there is no "Attribute2 " for a "Slot", I need to skip
that Slot.

I arrived at a regular exp similar to:
"^Slot:\\s+(.*? )\\s+Descriptio n:\\s+.*?\\s+At tribute1:\\s+.* ?\\s+Attribute2 :\\s+(.*?)\\s+. *?$"
but no luck. For the above example, this gives me "slot1 and attrd",
wheras I was expecting slot2, attrb and slot3, attrd.

Any thoughts on this is highly appreciated.
Can you show us a minimal but complete sample that demonstrates this
behavior? Your regular expression might be fine but your use of the
library might be in error.

Cheers! --M

Jul 11 '06 #4
On 11 Jul 2006 04:08:29 -0700 in comp.lang.c++,
de************* @yahoo.co.in wrote,
>I arrived at a regular exp similar to:
"^Slot:\\s+(.* ?)\\s+Descripti on:\\s+.*?\\s+A ttribute1:\\s+. *?\\s+Attribute 2:\\s+(.*?)\\s+ .*?$"
but no luck. For the above example, this gives me "slot1 and attrd",
wheras I was expecting slot2, attrb and slot3, attrd.

Any thoughts on this is highly appreciated.
My thoughts: your regex is too complex and troublesome for me.

Read your input line-by-line into a std::string with std::getline.
If you like regex, use it to parse the lines,
"([A-Za-z0-9]):(.*)" or suchlike.

When you have parts you can handle them sensibly, errors are not all
the same "regex failed" message to the poor user, etc.

Jul 11 '06 #5
de************* @yahoo.co.in wrote:
Hello,

I am relatively new to the world of regex and require some help in
forming a regular expression to achieve the following:

I have an input stream similar to:

Slot: slot1
Description: this is a description
Slot: slot2
Description: this is the second description
Attribute1: atrra
Attribute2: attrb
Slot: slot3
Description: this is the third description
Attribute1: atrrc
Attribute2: attrd

I have to pick all the values for "Slot" and corresponding
"Attribute2 ". If there is no "Attribute2 " for a "Slot", I need to skip
that Slot.

I arrived at a regular exp similar to:
"^Slot:\\s+(.*? )\\s+Descriptio n:\\s+.*?\\s+At tribute1:\\s+.* ?\\s+Attribute2 :\\s+(.*?)\\s+. *?$"
but no luck. For the above example, this gives me "slot1 and attrd",
wheras I was expecting slot2, attrb and slot3, attrd.

Any thoughts on this is highly appreciated.
As written, the regular expression requires the presence of all three of
Definition, Attribute1, and Attribute2 for a match. So with your
example, the Definition portion of the first Slot swallows all the input
up to Attribute1, that is, the definition field includes the beginnning
of the text for the next Slot.

You need to make the attributes optional. Change

"Attribute1:\\s +.*?\\s+"
to

"(?:Attribute1: \\s+.*?)?"

and similarly for attribute2. (Also take out the ^ an $; they're just
confusing the issue) That way you can pick out the first slot
definition. Then check whether it had an attribute 2, and if not, repeat
the search, starting at the first character after the match. In general
that kind of repetitive search is tricky to get right, so you're better
off letting the implementor handle the details. With TR1's regular
expressions, the code would look something like this:

using namespace std::tr1;

regex rgx( regular expression goes here );
const char *text = sample text goes here;
cregex_iterator first(text, text + strlen(text), rgx);
cregex_iterator last;
while (first != last)
{
if ((*first)[1].matched)
cout << *first << '\n';
++first;
}

For more details, see chapter 19 of my book, "The C++ Standard Library
Extensions," which will be in bookstores later this month. It covers all
of TR1.
Jul 11 '06 #6

"mlimber" <ml*****@gmail. comwrote:
Robbie Hatley wrote:
<de************ *@yahoo.co.inwr ote:
I am relatively new to the world of regex and require some help in
forming a regular expression...
This has absolutely nothing to do with C++. Ask this in a group
that deals more with regexes, like a Gnu utilities group, or
even a perl group:

gnu.utils.help
comp.lang.perl. misc

Also be aware that many programs that use regexes use non-standard
extensions. What program are you using your regexes with? Ask in
a group suitable for that program. Or call it's vendor on the phone.
Or visit the program's web site. Or read a book or manual on the
program. Or google for info on the program.

Not so! ... TR1 (a planned extension to the standard library)
has a regex component.
If so, awesome, bitchin', and cool. I had to write my own regex
routines (partly based a couple of non-standard, buggy regex
functions that come with my compiler) in order to do regexes in
my programs. It was a lot of hard work, doesn't always work right,
and is very unportable. If regex gets in the std. lib., that would
be awesome.

So perhaps I erred in my earlier comments. If so, my apologies
to you and the OP.
--
Cheers,
Robbie Hatley
East Tustin, CA, USA
lone wolf intj at pac bell dot net
(put "[usenet]" in subject to bypass spam filter)
http://home.pacbell.net/earnur/
Jul 14 '06 #7

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

7
7805
by: derek.google | last post by:
I hope a Boost question is not too off-topic here. It seems that upgrading to Boost 1.33 broke some old regex code that used to work. I have reduced the problem to this simple example: cout << boost::regex_replace(string("foo"), boost::regex(".*"), string("bar")) << endl; The above code prints "barbar" where I expect "bar". Can anyone shed some light on this? It used to work with 1.30 (though regex_replace
4
3228
by: Neri | last post by:
Some document processing program I write has to deal with documents that have headers and footers that are unnecessary for the main processing part. Therefore, I'm using a regular expression to go over each document, find out if it contains a header and/or a footer and extract only the main content part. The headers and the footers have no specific format and I have to detect and remove them using a list of strings that may appear as...
6
489
by: JohnSouth | last post by:
Hi I've been using a Regular expression to test for valid email addresses. It looks like: \w+(\w+)*@\w+(\w+)*\.\w+(\w+)* I've now had 2 occassions where it has rejected and email address with a "&" character in the local part. I know I should be able to work it out myself, but I'd like to ask anyone to suggest the best way to
3
2304
by: Joe | last post by:
Hi, I have been using a regular expression that I don’t uite understand to filter the valid email address. My regular expression is as follows: <asp:RegularExpressionValidator id="valValidEmail" runat="server" ControlToValidate="txtEmail" ValidationExpression="^(+)(\.+)*@(+)(\.+)*(\.{2,4})$"
18
3039
by: Q. John Chen | last post by:
I have Vidation Controls First One: Simple exluce certain special characters: say no a or b or c in the string: * Second One: I required date be entered in "MM/DD/YYYY" format: //+4 How ??
3
3218
by: James D. Marshall | last post by:
The issue at hand, I believe is my comprehension of using regular expression, specially to assist in replacing the expression with other text. using regular expression (\s*) my understanding is that this will one or more occurrences to replace all the white space between with a comma. This search ElseIf InStr(1, indivline, "$") Then insert a replace statement that uses the regular expression to find and replace all the white space...
7
3829
by: Billa | last post by:
Hi, I am replaceing a big string using different regular expressions (see some example at the end of the message). The problem is whenever I apply a "replace" it makes a new copy of string and I want to avoid that. My question here is if there is a way to pass either a memory stream or array of "find", "replace" expressions or any other way to avoid multiple copies of a string. Any help will be highly appreciated
3
1346
by: Lucky | last post by:
hi guys, i'm practising regular expression. i've got one string and i want it to split in groups. i was trying to make one regular expression but i didn't successed. please help me guys. i'm using .NET 2.0's Regular expression class. here is the string.
25
5163
by: Mike | last post by:
I have a regular expression (^(.+)(?=\s*).*\1 ) that results in matches. I would like to get what the actual regular expression is. In other words, when I apply ^(.+)(?=\s*).*\1 to " HEART (CONDUCTION DEFECT) 37.33/2 HEART (CONDUCTION DEFECT) WITH CATHETER 37.34/2 " the expression is "HEART (CONDUCTION DEFECT)". How do I gain access to the expression (not the matches) at runtime? Thanks, Mike
0
9500
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
0
9349
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
1
9285
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
0
9218
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
0
8227
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
1
6772
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
0
4575
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
1
3292
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
3
2199
bsmnconsultancy
by: bsmnconsultancy | last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.