?
Solved

search and replace

Posted on 1998-08-20
9
Medium Priority
?
189 Views
Last Modified: 2010-03-05
hello,
I would like to search a string for a pattern,but only delete the last occurrence of the pattern. For example:
  when string is:
      object1.a oject2.b object1
   pattern is
         object1
 after processing, string should become
     object1.a object2.b
however,when string is
   object1.a object2.b object1.c
the pattern is object1
  after processing
  the string still is:
  object1.a object2.b object1.c    
0
Comment
Question by:rongz
  • 4
  • 2
  • 2
  • +1
9 Comments
 
LVL 5

Expert Comment

by:ecw
ID: 1204427
$string =~ s/(object1)(.*)$1/$1$2/;
0
 
LVL 5

Expert Comment

by:ecw
ID: 1204428
Whoops missed the last bit of the question off

$string =~ s/(object1)(\.a.*)$1(?!\.c)/$1$2/;
0
 
LVL 5

Accepted Solution

by:
b2pi earned 300 total points
ID: 1204429
ecw, what happens if it's in there more than twice?

For general purposes, try:

$pattern = 'object1'; ## or what have you
$string =~ s/(.*\s)$a(\s.*?|$)/$1$2/;

Note that this will NOT remove the pattern if the only occurence of the pattern is the first thing on the line. It will, however, remove the pattern even if the pattern is not duplicated.
If you don't want that to happen, use

$string =~ s/($a.*\s)$a(\s.*?|$)/$1$2/;


0
Upgrade your Question Security!

Your question, your audience. Choose who sees your identity—and your question—with question security.

 

Author Comment

by:rongz
ID: 1204430
I tried the solution. Not work. What's the $a.
Is there any potential problem with following:

$string=~s/([.\s]*)($pattern$)/$1;
0
 

Author Comment

by:rongz
ID: 1204431
I tried the solution. Not work. What's the $a.
Is there any potential problem with following:

$string=~s/([.\s]*)($pattern$)/$1;
0
 

Author Comment

by:rongz
ID: 1204432
I tried the solution. Not work. What's the $a.
Is there any potential problem with following:

$string=~s/([.\s]*)($pattern$)/$1;
0
 
LVL 5

Expert Comment

by:b2pi
ID: 1204433
<brain cramp>
Use $pattern where it says $a

potential problems with "$string=~s/([.\s]*)($pattern$)/$1;" ?
1.) It won't compile (no trailing /)
2.) it will ONLY work if pattern is at the very end of the string (that also means that
    the line "object1.a object1.b object1 " where $pattern is object1 will leave you with
               "object1.a object1.b object1 "
                                                        ^ see the blasted space? This kind of problem will bite you forever)
3.) if pattern is "object" it will take "object notanobject" and make it into "object notan"

0
 
LVL 85

Expert Comment

by:ozo
ID: 1204434
s/\b\Q$pattern\E(\s*)$/$1/;
0
 

Author Comment

by:rongz
ID: 1204435
thanks all
0

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Email validation in proper way is  very important validation required in any web pages. This code is self explainable except that Regular Expression which I used for pattern matching. I originally published as a thread on my website : http://www…
I have been pestered over the years to produce and distribute regular data extracts, and often the request have explicitly requested the data be emailed as an Excel attachement; specifically Excel, as it appears: CSV files confuse (no Red or Green h…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
Six Sigma Control Plans

568 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question