File parsing in Perl

Question

I am trying to parse a file in the following format.

Case1: 0x5sdf258:648s4df ..;. ABCD hhbdch ; extra text 
Case2: 0xdef58e1:18w4we1 .... HCDC ajdknlmk ;extra text

I want to remove the extra text after the semicolon, So I use the following line

   $row =~ s/;.*//g;

This works in case 2 but fails in case 1. Is there a method in which I can perform my task in both the cases?

Avinash Raj · Accepted Answer · 2015-03-09 09:21:38Z

1

Seems like you want something like this,

$row =~ s/;[^;]*$//g;

OR

$row =~ s/;[^;\n]*$//g;

This would remove the text after the last semicolon (including semicolon).

DEMO

[^;]* negated character class which matches any charcater but not of ; , zero or more times.
$ asserts that we are at the end.

Code:

use strict;
use warnings;

while(my $line = <DATA>) {
    $line =~ s/;[^;]*$//g;
    print $line."\n";
}


__DATA__
Case1: 0x5sdf258:648s4df ..;. ABCD hhbdch ; extra text 
Case2: 0xdef58e1:18w4we1 .... HCDC ajdknlmk ;extra text

Output:

Case1: 0x5sdf258:648s4df ..;. ABCD hhbdch 
Case2: 0xdef58e1:18w4we1 .... HCDC ajdknlmk

edited Mar 9, 2015 at 9:21

answered Mar 9, 2015 at 9:01

Avinash Raj

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3 Comments

LearningToCode Over a year ago

I don't know the reason but it didn't work for me... Can you provide me an explanation?

LearningToCode Over a year ago

I don't know how it works in this demo. In actual code it still fails. I have already chomped the line.

LearningToCode Over a year ago

Anyways I figured out another method: $row =~ s/(0x[0-9a-f]+:\s+\w+\s+....\s+.*);.*$/$1/g; Case1 and Case2 text are not a part of line.

vks · Accepted Answer · 2015-03-09 09:01:49Z

0

;(?!.*;).*

Try this.See demo.

https://regex101.com/r/eS7gD7/30

answered Mar 9, 2015 at 9:01

vks

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1 Comment

Len Jaffe Over a year ago

This regex, which should have been explained by its poster, finds a semi-colon, that is not followed by any other semi-colons. But I fear that it uses an inefficient method to arrive at an answer, using a zero-width negative lookahead assertion.

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