Substituting white spaces with a tab changes my string into numeric value

[PerlPeer]

hi, I try to replace white spaces with tabs, but my string gets changed into a numeric value after that. I wrote the basic step as a new program to show what happens

#!/usr/bin/perl -w
use strict;

$_ = "CC1G_00040T0    NODE_4204_length_20667_cov_33.873905_4    3e-46"
+;

my $line = $_;
print "$line\n";
$line = s/\s+/\t/g;
print "$line\n";

when I run this, it gives the following:

CC1G_00040T0 NODE_4204_length_20667_cov_33.873905_4 3e-46

2

How can I prevent my string from becoming a numeric value?

[remiah]

change

$line = s/\s+/\t/g;

to

$line =~ s/\s+/\t/g;

[PerlPeer]

Thanks!

[dsheroh]

To explain what was going on here:

s/\s+/\t/g; is equivalent to $_ =~ s/\s+/\t/g;, so $line =~ s/\s+/\t/g; actually means $line = ($_ =~ s/\s+/\t/g); (The parentheses aren't actually necessary, but I wanted to make the precedence completely clear.)

In scalar context, a regex match or substitution (=~) returns the number of matches found/substitutions performed, so, to finally get to where that 2 comes from, $line =~ s/\s+/\t/g; changes all the groups of whitespace in $_ into tabs and sets $line to the number of substitutions which were performed. If you look at $_, you will find that it holds the value you wanted, since $line and $_ held the same value before the substitution was performed.

[PerlPeer]

Thank you too.

I figured that somehow I got a numerical value of the number of tabs, since when I used:

 s/\s+/\t/

(thus without the "g") the number that was returned was 1 (instead of 2). I had no idea however, how this was caused.

I frequently fail to recognize this kind of "equivalents". I hope this is just being new to perl.......