Is $data binary or ascii?

[Dan Muey]

Say I have a variable $data that has file contents in it.
Is there a way to tell if it is binary or ascii?

if($data =~ ???) { print "It is binary weeee"; }
elsif($data =~ ???) { print "It is ascii woo hoo"; }
else { print "I do not know what it is, doh!"; }

TIA

Dan

[Paul Kraus]

if -T ("looks like text file")
If -B ("looks like binary file")

if -T $data ....
if -B $data ....

HTH
Paul
-----Original Message-----
From: Dan Muey [mailto:dmuey@infiniplex.com]
Sent: Tuesday, September 09, 2003 11:57 AM
To: [email]beginners@perl.org[/email]
Subject: Is $data binary or ascii?


Say I have a variable $data that has file contents in it.
Is there a way to tell if it is binary or ascii?

if($data =~ ???) { print "It is binary weeee"; }
elsif($data =~ ???) { print "It is ascii woo hoo"; }
else { print "I do not know what it is, doh!"; }

TIA

Dan

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[Dan Muey]

> if -T ("looks like text file")
> If -B ("looks like binary file")
>
> if -T $data ....
> if -B $data ....
>
> HTH

Definitely! Thanks Paul.
I never thought of using the file test operators on variables!
Cool.

Thanks!

> Paul
> -----Original Message-----
> From: Dan Muey [mailto:dmuey@infiniplex.com]
> Sent: Tuesday, September 09, 2003 11:57 AM
> To: [email]beginners@perl.org[/email]
> Subject: Is $data binary or ascii?
>
>
> Say I have a variable $data that has file contents in it.
> Is there a way to tell if it is binary or ascii?
>
> if($data =~ ???) { print "It is binary weeee"; }
> elsif($data =~ ???) { print "It is ascii woo hoo"; }
> else { print "I do not know what it is, doh!"; }
>
> TIA
>
> Dan
>
> --
> To unsubscribe, e-mail: [email]beginners-unsubscribe@perl.org[/email]
> For additional commands, e-mail: [email]beginners-help@perl.org[/email]
>
>

[Jeff 'Japhy' Pinyan]

On Sep 9, Dan Muey said:

>> if -T $data ....
>> if -B $data ....

>
>I never thought of using the file test operators on variables!

I'm not so sure you can. But the docs say that -B looks for at least 30%
of the characters to be control-chars or high-bit chars. So I'd suggest:

sub is_binary_data {
local $_ = shift;
(tr/ -~//c / length) >= .3;
}

The tr/ -~//c takes the range of characters from space to tilde (32-126),
inverts it (so characters 0-31 and 127-255), and counts how many of them
are in $_. Then we divide that by the length of the string. If that's at
least .3, that means at least 30% of the string is binary data.

--
Jeff "japhy" Pinyan [email]japhy@pobox.com[/email] [url]http://www.pobox.com/~japhy/[/url]
RPI Acacia brother #734 [url]http://www.perlmonks.org/[/url] [url]http://www.cpan.org/[/url]
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
[ I'm looking for programming work. If you like my work, let me know. ]

[Dan Muey]

> On Sep 9, Dan Muey said:

>

> >> if -T $data ....
> >> if -B $data ....

> >
> >I never thought of using the file test operators on variables!

>
> I'm not so sure you can. But the docs say that -B looks for

I was afraid of that. After trying it out I couldn't get any good results.

> at least 30% of the characters to be control-chars or
> high-bit chars. So I'd suggest:
>
>
> sub is_binary_data {
> local $_ = shift;
> (tr/ -~//c / length) >= .3;
> }
>
> The tr/ -~//c takes the range of characters from space to
> tilde (32-126), inverts it (so characters 0-31 and 127-255),
> and counts how many of them are in $_. Then we divide that
> by the length of the string. If that's at least .3, that
> means at least 30% of the string is binary data.
>

Excellent! Since the -B needed to be a file I was thinking about how to mimik the -B option.
That is excellent, thanks for the explanation and info!

Thanks Jeff!
Dan

> --
> Jeff "japhy" Pinyan [email]japhy@pobox.com[/email]

[John W. Krahn]

Dan Muey wrote:

>
> Say I have a variable $data that has file contents in it.
> Is there a way to tell if it is binary or ascii?
>
> if($data =~ ???) { print "It is binary weeee"; }
> elsif($data =~ ???) { print "It is ascii woo hoo"; }
> else { print "I do not know what it is, doh!"; }

if ( $data =~ /[^[:ascii:]]/ ) {
print "\$data contains non-ASCII characters\n";
}
else {
print "\$data contains only ASCII characters\n";
}



John
--
use Perl;
program
fulfillment

[Dan Muey]

> Dan Muey wrote:

> >
> > Say I have a variable $data that has file contents in it.
> > Is there a way to tell if it is binary or ascii?
> >
> > if($data =~ ???) { print "It is binary weeee"; }
> > elsif($data =~ ???) { print "It is ascii woo hoo"; }
> > else { print "I do not know what it is, doh!"; }

>
>
> if ( $data =~ /[^[:ascii:]]/ ) {
> print "\$data contains non-ASCII characters\n";
> }
> else {
> print "\$data contains only ASCII characters\n";
> }

Interesting John.
Anyone know where is the [:ascii:] class/group/whatever you call it documented?
I'd like to get more info on it to compare the other method mentioned earlier in the thread,
{which works good on all my tests so far)

Thanks

Dan

>
>
>
> John

[John W. Krahn]

Dan Muey wrote:

>
> Anyone know where is the [:ascii:] class/group/whatever you call it documented?

perldoc perlre


John
--
use Perl;
program
fulfillment

[Dan Muey]

> Dan Muey wrote:

> >
> > Anyone know where is the [:ascii:] class/group/whatever you call it
> > documented?

>
> perldoc perlre

Thanks I'll have a look then!

>
>
> John
> --
> use Perl;
> program
> fulfillment
>
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> To unsubscribe, e-mail: [email]beginners-unsubscribe@perl.org[/email]
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>
>

[Dan Muey]

> > Dan Muey wrote:

> > >
> > > Anyone know where is the [:ascii:] class/group/whatever

> you call it

> > > documented?

> >
> > perldoc perlre

>
> Thanks I'll have a look then!

Looks like it's a Posix thing added in 5.8.0 which is cool and can be written as
[:^ascii:]
Instead of [^[:ascii:]]

Very cool, although it only works on my 5.8.0 and not 5.0
(I don't have a 5.6 ish anyone know when the Posix support was added to regexes?)

This could be usefull if I could do
if($perlversion >= 5.8.0) { do the posix [:^ascii:] version }
Else { do it the -B emulation way }

Anyone know how to check the version without putting use 5.8.0; at the top?
Dan

>

> >
> >
> > John
> > --
> > use Perl;
> > program
> > fulfillment
> >
> > --
> > To unsubscribe, e-mail: [email]beginners-unsubscribe@perl.org[/email]
> > For additional commands, e-mail: [email]beginners-help@perl.org[/email]
> >
> >

>
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>
>

[James Edward Gray II]

On Tuesday, September 9, 2003, at 01:28 PM, Dan Muey wrote:

> Looks like it's a Posix thing added in 5.8.0 which is cool and can be
> written as
> [:^ascii:]
> Instead of [^[:ascii:]]
>
> Very cool, although it only works on my 5.8.0 and not 5.0
> (I don't have a 5.6 ish anyone know when the Posix support was added
> to regexes?)

I don't know the version it was added in, but it works in Perl 5.6.0.

James

[Dan Muey]

> On Tuesday, September 9, 2003, at 01:28 PM, Dan Muey wrote:

>

> > Looks like it's a Posix thing added in 5.8.0 which is cool

> and can be

> > written as
> > [:^ascii:]
> > Instead of [^[:ascii:]]
> >
> > Very cool, although it only works on my 5.8.0 and not 5.0
> > (I don't have a 5.6 ish anyone know when the Posix support was added
> > to regexes?)

>
> I don't know the version it was added in, but it works in Perl 5.6.0.

Yeah 5.6.0 had a lot of goodies like that added. It was probably then.
Anybody else then, 5.6.0 going once going twice....

>
> James
>
>

[John W. Krahn]

James Edward Gray II wrote:

>
> On Tuesday, September 9, 2003, at 01:28 PM, Dan Muey wrote:
>

> > Looks like it's a Posix thing added in 5.8.0 which is cool and can be
> > written as
> > [:^ascii:]
> > Instead of [^[:ascii:]]
> >
> > Very cool, although it only works on my 5.8.0 and not 5.0
> > (I don't have a 5.6 ish anyone know when the Posix support was added
> > to regexes?)

>
> I don't know the version it was added in, but it works in Perl 5.6.0.

It was added to Perl 5.6.0.

perldoc perldelta
[snip]
POSIX character class syntax [: :] supported

For example to match alphabetic characters use
/[[:alpha:]]/. See the perlre manpage for details.

$ perl -v

This is perl, v5.6.0 built for i586-linux




John
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