Replacing the pattern to search for

agynr has asked for the wisdom of the Perl Monks concerning the following question:

Hello Everyone, I am using the following code to search for the required pattern if in that document .

seek(INPUT,$start_offset_target,0);
sysread(INPUT,$target_data,$end_offset_target-$start_offset_target+1 )
+;    
while ($target_data=~m/$pattern/gi)

                            {                    
                            
                            
                                $space='';
                                $c=0;
                                 $m = $1;                             
+                 
                                while($m=~/(\n)/gi)
                                {
                                 $c+=1;
                                }
                                $space=' ' x $c;
                                $space.=' ' x length($m);
                                $target_data=~s/$pattern/$space/i;
                            }
[download]

Cau plz suggest any further Improvement that can be done . P.S. The $target_data can contain 100000 bytes anf the required $pattern can be found many a times.

Comment on Replacing the pattern to search for Download Code

Replies are listed 'Best First'.
Re: Replacing the pattern to search for by mkirank (Chaplain) on Jan 18, 2005 at 13:26 UTC
you can do it at the command line `perl -pi -e 's/<your pattern>/" " x (length($&))/eg' file` [download]	[reply] [d/l]
Re: Replacing the pattern to search for by sasikumar (Monk) on Jan 18, 2005 at 11:44 UTC
Hi What r u trying to solve. i am not sure why you have two while loops. Please let us know what is the input to it. What would be the output too. This could help us to get to resolve the problem that you face.As far us now i can just understand that you are replacing a pattern with another one that will have space and length of the pattern. Please let us knwo what you want clearly with a example so that we could help you. Thanks SasiKumar	[reply]
Re^2: Replacing the pattern to search for by agynr (Acolyte) on Jan 18, 2005 at 11:52 UTC
Actually the thing is that I want to retain the size of the code by inserting the space whereever that particular $pattern exists. The second while is used as there can be any no. of lines before there the pattern is found.	[reply]
Re^3: Replacing the pattern to search for by sasikumar (Monk) on Jan 18, 2005 at 12:05 UTC
So here is the code `use strict; my $file_name="c:\\temp.txt"; open (FH,"$file_name"); my $pattern="some thing"; my $c=0; my $space=' '; my $line; while(<FH>) { $line=$_; #current line $c++; #counts the number of lines $space=' ' x $c .' ' x length($pattern); #pattern that has to be r +eplaced $line=~s/$pattern/$space/i; }` [download] Thanks SasiKumar	[reply] [d/l]
Re: Replacing the pattern to search for by TedPride (Priest) on Jan 18, 2005 at 15:46 UTC
Not sure what exactly you're trying to do, but it looks like you want pattern replaced with line number (starting at 1) + pattern length number of spaces. You also want to do this only once per line. In addition, the file is specified as being up to 100000 bytes, which means the file can be loaded into memory all at once instead of being read line by line. The following should work: `use strict; use warnings; my $path = "c:\\temp.txt"; my $pattern = "some thing"; my $handle; open($handle, $path); my @data = <$handle>; close($handle); my $c = length($pattern); for (@data) { $c++; $_ =~ s/$pattern/' ' x $c/ei; } open($handle, ">$path"); print $handle @data; close($handle);` [download]	[reply] [d/l]