Question

Good Day,

I have a simple working routine in Perl that swaps two words:

i.e. John Doe —–> Doe John

Here it is:

sub SwapTokens()
{
    my ($currentToken) = @_;

    $currentToken =~ s/([A-Za-z]+) ([A-Za-z]+)/$2 $1/;
    # $currentToken =~ s/(\u\L) (\u\L)/$2 $1/;
    return $currentToken;
} 

The following usage yields exactly what I want:

print &SwapTokens("John Doe");

But when I uncomment out the line ‘$currentToken =~ s/(\u\L) (\u\L)/$2 $1/;

I get an error. Am I missing something, it looks like my syntax is correct.

TIA,

coson

Answer 1

\L means “lowercase till \E“; i.e., it needs to be followed at some point by \E. You do not have \E in your regex, thus it is not valid; adding \E after each \L gets the script to compile, though I have no idea what you are actually trying to accomplish there.