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remove substring and assign to new var

cauliflower
New User

Sep 2, 2016, 2:43 AM

Post #1 of 7 (4942 views)

remove substring and assign to new var	Can't Post

Hi,

I see I can remove a substring like:

$sentence =~ s/substring//;

But I want to assign the resulting string to a new var, I want to leave $sentence unchanged. So I'd have a new var which was $sentence minus the substring. I hope that makes sense?

cauliflower
New User

Sep 2, 2016, 3:11 AM

Post #2 of 7 (4941 views)

Re: [cauliflower] remove substring and assign to new var [In reply to]	Can't Post

I think I found an answer using brackets:

($sentence2 = $sentence) =~ s/substring//;

BillKSmith
Veteran

Sep 2, 2016, 7:03 AM

Post #3 of 7 (4936 views)

Re: [cauliflower] remove substring and assign to new var [In reply to]	Can't Post

Unless you have a very old version of perl, you can use the /r option.

Code

$sentence2 = $sentence =~ s/substring//r;

It does not make much difference which way you choose unless your original sentence is already in $_.

Code

C:\Users\Bill\perl\guru>type cauliflower.pl 
use strict; 
use warnings; 
$_ = 'The quick brown fox jumps.'; 
my $sentence2 = s/quick\s//r; 
print $sentence2, "\n"; 
 
C:\Users\Bill\perl\guru>cauliflower.pl 
The brown fox jumps.

Good Luck,
Bill

cauliflower
New User

Sep 2, 2016, 10:05 AM

Post #4 of 7 (4929 views)

Re: [BillKSmith] remove substring and assign to new var [In reply to]	Can't Post

Hmmm that didn't seem to work for me, but we are running v5.8.0, which I guess is pretty old!

FishMonger
Veteran / Moderator

Sep 2, 2016, 10:16 AM

Post #5 of 7 (4927 views)

Re: [cauliflower] remove substring and assign to new var [In reply to]	Can't Post

Quote

I want to assign the resulting string to a new var, I want to leave $sentence unchanged.

If you don't want to modify the original var, then don't use a substitution regex.

Code

my $sentence = 'The quick brown fox jumps.';  
my ($sentence2) = $sentence =~ /\s(quick)\s/;  
print $sentence2, "\n";

Quote

C:\test>test.pl
quick

I may have misinterpreted your goal, so if that doesn't do what you want, then please clarify your need.

(This post was edited by FishMonger on Sep 2, 2016, 10:18 AM)

cauliflower
New User

Sep 2, 2016, 11:48 AM

Post #6 of 7 (4918 views)

Re: [FishMonger] remove substring and assign to new var [In reply to]	Can't Post

In Reply To

Quote

I want to assign the resulting string to a new var, I want to leave $sentence unchanged.

If you don't want to modify the original var, then don't use a substitution regex.

Code

my $sentence = 'The quick brown fox jumps.';  
my ($sentence2) = $sentence =~ /\s(quick)\s/;  
print $sentence2, "\n";

Quote

C:\test>test.pl
quick

I may have misinterpreted your goal, so if that doesn't do what you want, then please clarify your need.

Thanks,

In your example what I would actually want sentence2 to be is "The brown fox".

What I ended up needing was to substitute in another string, I'm actually using this format which seems to work:

($sentence2 = $sentence) =~ s/quick/slow/;

Making sentence2 "The slow brown fox"

BillKSmith
Veteran

Sep 2, 2016, 3:06 PM

Post #7 of 7 (4909 views)

Re: [cauliflower] remove substring and assign to new var [In reply to]	Can't Post

"Non-Destructive Substitution" (s///r) was added in version 5.14.0.

I consider your approach to the original task as excellent with the older perl and still acceptable with newer versions. I do not understand your reply to FishMonger. Perhaps if you explain your new requirements we can suggest a better solution.
Good Luck,
Bill

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