To remove the newline character of a variable in perl

Question

I have my perl code like this

my $test = "gsfdsd gsfgsfg sfghsdg 
Starting 
gahgahd vvsfdh";

$test=~ m/(.*)Starting(.*)/;
print"test value = $1 \n";

when I execute this code, I get nothing ie,

test value =  

But when the $test strings are in the same line ie,

my $test ="gsfdsd gsfgsfg sfghsdg Starting gahgahd vvsfdh"; 

I get the result for the print statement to be

test value = gsfdsd gsfgsfg sfghsdg.

What's the problem with the first case. The only difference is the inclusion of newline space. How to make the first code get executed.

Answer 1

The s modifier to regexes causes . to match newlines.

So your regex should be

$test=~ m/(.*)Starting(.*)/s;

to get the behaviour you want.

Answer 2

The dot doesn't match a newline unless you use the /s modifier.

$test =~ /(.*)Starting(.*)/s;

Are you sure you want the newlines to be part of the captured strings?

Answer 3

Other answers have corrected your regex. But if your goal is to split a string into lines, use split .

use strict;
use warnings;
use v5.10;

my $test = "gsfdsd gsfgsfg sfghsdg 
Starting 
gahgahd vvsfdh";
my @lines = split /\n/, $test;
say "First line:  $lines[0]";
say "Second line: $lines[1]";
say "Third line:  $lines[2]";

If your goal is to get the first and third lines, using split means you don't need to know what the content of the second line is.

Answer 4

As others have said, . matches any character except newline, so your .* won't match beyond the end of the line

You can simply account for that whitespace using \\s* . \\s matches any whitespace character, and newline is a whitespace character

my $test = "gsfdsd gsfgsfg sfghsdg 
Starting 
gahgahd vvsfdh";

$test =~ m/(.*)\s*Starting/;
print "test value = $1 \n";

output

test value = gsfdsd gsfgsfg sfghsdg  

Answer 5

It is very simple to achieve the solution using substitution and multi-line matching.

#!/usr/bin/perl 
use strict;
use warnings;

my $test = "gsfdsd gsfgsfg sfghsdg 
Starting 
gahgahd vvsfdh";

$test=~ s/\n//mg;
print"test value = $test \n";

The output is as below,

test value = gsfdsd gsfgsfg sfghsdg Starting gahgahd vvsfdh