Question

RegExpr : Find and Replace last occurrence of a space(ASCII 20) in a line of text

Asked by: mhotto

Zum Alles,

Given the string:
"xxxxx x xxxxxxxxxx","nnnn xxxxxxxxxxxxxxx","xxxxxxx xx nnnnn/lf
I want to find and replace the last occurence of '  ' in the line of text with a ", to give me the following:
"xxxxx x xxxxxxxxxx","nnnn xxxxxxxxxxxxxxx","xxxxxxx xx "nnnnn/lf

This REGEX " ^*\s " finds the first space in line.  I can not figure out a REGEX to find the last space in the line.

Any help would be appreciated.

Thanks

Mike

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-07-02 at 09:58:37ID24540249
Tags

Regular Expression

,

PERL

,

REGEX

Topic

Perl Programming Language

Participating Experts
3
Points
275
Comments
12

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Solaris Prints ASCII Files with LF and no CR
    I have one Lexmark printer setup on my Solaris 2.6 box which works great. I am trying to set up a second. Both are networked printers, and the print spool should reside on the Solaris box. When I create the the printer, it does the following: using lpadmin: prints ASCII...
  2. transform the CR/LF characters to \r\n
    I have text data from FoxPro (memo). There are a few paragraphs in a single transaction that I pull back into a WIN FORM dataset to present in a textbox. No edit here, just read only. What is the best way to repalce the CR/LF with the escape sequences that my WinForms will...
  3. ASCII FS and ASCII LF characters
    In a VB mapping program, I am mapping data from a text file into another text file, and am supposed to use the ASCII FS character as the field terminator, and the ASCII LF character as the record terminator. Usually, field terminators are just a comma, or the character "...
  4. Regex return all ascii characters and CR/LF but exclude e…
    How can I get a Regex pattern that will return all ascii characters and CR/LF but exclude everything else - especially all other non-printable characaters. Thanks. James.
  5. RegEx for removing two+ CR/LF in a string
    Hey experts, I'm having some trouble sucessfully creating a Regex to replace single instances of CR/LF (Carriage Return followed by a Line Feed) in a string. Meaning if there is one by itsself, strip it out, but if there are two or more together then they should stay. My c...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: bounsyPosted on 2009-07-02 at 10:45:22ID: 24765756

In Perl regex:

s/(.*) /$1"/

                                              
1:

Select allOpen in new window

 

by: bounsyPosted on 2009-07-02 at 10:46:18ID: 24765766

Alternately:

s/ (?=[^ ]*$)/"/

                                              
1:

Select allOpen in new window

 

by: bounsyPosted on 2009-07-02 at 10:53:58ID: 24765835

Note also that "\s" in your original regex matches any whitespace character (space, tab, etc.), not just a regular space.

 

by: ghostdog74Posted on 2009-07-02 at 20:16:41ID: 24769569

$\ = "\n";              
while (<>) {
    chomp;      # strip record separator
    @f = split(/\s+/, $_);
    $f[-1] = " \"" . $f[-1];
    print join($,,@f);
}

                                              
1:
2:
3:
4:
5:
6:
7:

Select allOpen in new window

 

by: Adam314Posted on 2009-07-06 at 08:18:16ID: 24786050

ghostdog74 - that also has the side effect of replacing all groups of spaces with $,.  Even if $, is set to " ", you still replace multiple spaces with a single space.

 

by: mhottoPosted on 2009-07-07 at 07:03:17ID: 24794298

To all:  For learning/instructional/testing purposes, I am using The Regex Coach - interactive regular expressions(The Regex Coach is Copyright © 2003-2004 Dr. Edmund Weitz - All Rights Reserved. http://weitz.de/regex-coach/) to test solutions presented.  Using REGEX COACH, I have been unable to just find the last space in the line.

I need to simply my initial problem request to two parts.

First part of question, and most significant part.

1)Find last space in line of text.
2)Replace that single space with a single "

Thanks

Mike

 

by: mhottoPosted on 2009-07-07 at 07:38:31ID: 24794617

Zum Alles:  Test Example.
"Xxxxx X Xx-xxxxxxx","3037 RANDOLPH STREET","Xxxxxxx NE 68510
This REGEX
\s.....$
  highlighs/finds

 68510
I need to find/highlight only the space before the 6.  Or more generalized.  The final space in text string.

Viel Dank

Mike

 

by: bounsyPosted on 2009-07-07 at 08:17:35ID: 24795014

This works for me in Regex Coach.  Note that there is a sinle space character before the open paren and nothing after the closing paren.

 (?=[^ ]*$)

                                              
1:

Select allOpen in new window

 

by: mhottoPosted on 2009-07-07 at 09:59:47ID: 24795984

Bounsy,

Points are yours.  You answered my primary question, but before I close this out.  Is it possible to find the space using
    \Z  Match only at end of string, or before newline at the end
    \z  Match only at end of string
Also, using REGEX COACH, what is the replace code

to replace space w "

Thanks

Mike

 

by: bounsyPosted on 2009-07-07 at 10:26:34ID: 24796245

The replacement string is just a single double quote character.

As for \Z or \z, they serve similar functions to the $ token.  Which one you use really depends on your data and what your regex modifiers are.  In most cases (simple, single-line strings with an optional carriage return at the end and no embedded carriage returns in the middle), the $ is used and does what you are looking for.  Regex Coach is great for helping you see what happens if your Target string contains multiple lines, what happens if the "m" or "s" regex modifiers are turned on, etc.

One thing you might also want to try (if you haven't already) is the Step functionality in Regex Coach that allows you to see exactly how the computer "executes" your regular expressions.  It can be eye-opening at times to see how efficient or inefficient some regular expressions can be.  It also can help you build a regular expression if you can see where the one you were working on strays from the behavior you are after.

 

by: mhottoPosted on 2009-07-07 at 11:23:34ID: 24796814

Thanks, Bounsy.  Appreciate your taking time to explain it.

Mike

 

by: mhottoPosted on 2009-07-07 at 11:26:46ID: 31599281

Bounsy, provided the specific solution I, required, with the same tool I, was using.  Bounsy, also added additional explanation.  Excellent Response.

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...