Use the substitution operator to move a minus sign at the end of the string (if any) to the front of the string: 
use warnings;
use strict;

while (<DATA>) {
    chomp;
    s/(.+)-$/-$1/;
    print "$_\n";
}

__DATA__
1.05
-5.66
7.89-

[download]

Outputs: 

1.05
-5.66
-7.89

[download]

In reply to Re: Proper creation of a negative number by toolic
in thread Proper creation of a negative number by insta.gator

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