Concatenation: $i.$j different from "$i$j"

{
my $i = "TT";
my $j = "AT";

if ("$i$j" =~ /X/)
{
print "$i$j matched\n";
}
else
{
print "$i$j not matched\n";
}
}

{
my $i = "TT";
my $j = "AT";

if ($i.$j =~ /X/)
{
print $i.$j . " matched\n";
}
else
{
print $i.$j . " not matched\n";
}
}

gives

TTAT not matched
TTAT matched

Can anyone explain?

Re: Concatenation: $i.$j different from "$i$j"

Occidental wrote:

>
> if ($i.$j =~ /X/)

> Can anyone explain?

Precedence can. =~ is two lines above . in the perlop list of
precedences.

$ perl -MO=Deparse,-p -e ' "x"."y" =~ /f/'
('x' . ('y' =~ /f/));
-e syntax OK

Xho

--
-------------------- http://NewsReader.Com/ --------------------
The costs of publication of this article were defrayed in part by the
payment of page charges. This article must therefore be hereby marked
advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate
this fact.

Re: Concatenation: $i.$j different from "$i$j"

Occidental wrote:
> {
> my $i = "TT";
> my $j = "AT";
>
> if ("$i$j" =~ /X/)
> {
> print "$i$j matched\n";
> }
> else
> {
> print "$i$j not matched\n";
> }
> }
>
> {
> my $i = "TT";
> my $j = "AT";
>
> if ($i.$j =~ /X/)
> {
> print $i.$j . " matched\n";
> }
> else
> {
> print $i.$j . " not matched\n";
> }
> }
>
> gives
>
> TTAT not matched
> TTAT matched
>
> Can anyone explain?

Yes, perl can:

$ perl -MO=Deparse,-p -e'
{
my $i = "TT";
my $j = "AT";

if ("$i$j" =~ /X/)
{
print "$i$j matched\n";
}
else
{
print "$i$j not matched\n";
}
}

{
my $i = "TT";
my $j = "AT";

if ($i.$j =~ /X/)
{
print $i.$j . " matched\n";
}
else
{
print $i.$j . " not matched\n";
}
}
'
{
(my $i = 'TT');
(my $j = 'AT');
if (("$i$j" =~ /X/)) {
print("$i$j matched\n");
}
else {
print("$i$j not matched\n");
}
}
{
(my $i = 'TT');
(my $j = 'AT');
if (($i . ($j =~ /X/))) {
print((($i . $j) . " matched\n"));
}
else {
print((($i . $j) . " not matched\n"));
}
}
-e syntax OK


if (("$i$j" =~ /X/)) {

Is false because there is no 'X' in 'TTAT'.

if (($i . ($j =~ /X/))) {

Is true because the string from the expression ($i . ($j =~ /X/)) is true.



John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall

Re: Concatenation: $i.$j different from "$i$j"

Occidental schreef:

> if ("$i$j" =~ /X/)
> if ($i.$j =~ /X/)

I heard somewhere that the next version of Python will make

1+2 * 3

behave differently from

1 + 2*3

;)

--
Affijn, Ruud

"Gewoon is een tijger."

Re: Concatenation: $i.$j different from "$i$j"

_
Dr.Ruud (rvtol+news@isolution.nl) wrote on VCXXXIV September MCMXCIII in
:
%% Occidental schreef:
%%
%% > if ("$i$j" =~ /X/)
%% > if ($i.$j =~ /X/)
%%
%% I heard somewhere that the next version of Python will make
%%
%% 1+2 * 3
%%
%% behave differently from
%%
%% 1 + 2*3
%%


If you had written 'Perl6' instead of 'Python', I would have assumed
you were serieus.


Abigail
--
map{${+chr}=chr}map{$_=>$_^ord$"}$=+$]..3*$=/2;
print "$J$u$s$t $a$n$o$t$h$e$r $P$e$r$l $H$a$c$k$e$r\n";

Re: Concatenation: $i.$j different from "$i$j"

Abigail schreef:
> Dr.Ruud:
>> Occidental:

>>> if ("$i$j" =~ /X/)
>>> if ($i.$j =~ /X/)
>>
>> I heard somewhere that the next version of Python will make
>>
>> 1+2 * 3
>>
>> behave differently from
>>
>> 1 + 2*3
>
> If you had written 'Perl6' instead of 'Python', I would have assumed
> you were serieus.

Hey, I was just aiming for a bigger publiek.

--
Affijn, Ruud (actually likes Perl6)

"Gewoon is een tijger."