Expression Problem

[Noname]

Hi,
I have input from STDIN like $Input="1-5,6,8,10-15";
which actually needs to be interpreted as an
array=1,2,3,4,5,6,8,10,11,12,13,14,15
how can it be done,

 

[Anno Siegel]

Hi,
I have input from STDIN like $Input="1-5,6,8,10-15";
which actually needs to be interpreted as an
array=1,2,3,4,5,6,8,10,11,12,13,14,15
how can it be done,

map /(\d+)-(\d+)/ ? $1 .. $2 : $_, split /,/, $Input;

Anno

 

[Paul GABORIT]

À (at) Tue, 10 Aug 2004 07:56:38 GMT,

I have input from STDIN like $Input="1-5,6,8,10-15";
which actually needs to be interpreted as an
array=1,2,3,4,5,6,8,10,11,12,13,14,15
how can it be done,

my @array = map {m/(.*)-(.*)/?($1..$2):$_} split ',', $Input;

 

[Sam Holden]

my @array = map { s/-/../; eval } split /,/, $Input;

evaling arbitrary text from STDIN isn't always a great idea. Sometimes
it is - but the in all those cases the user would be told that perl
expressions were expected...

Something like:

my @array = map {/^(\d+)-(\d+)$/?($1..$2):$_} split /,/, $Input;

would be a little safer.

 

[Tassilo v. Parseval]

Also sprach Bernard El-Hagin:

my @array = map { s/-/../; eval } split /,/, $Input;

Heh, cool. The split() isn't necessary, though:

my @array = map { s/-/../g; eval } $Input;

Tassilo

 

[gnari]

my @array = map { s/-/../; eval } split /,/, $Input;

please do not do this unless you trust the input 100% to
be in the format described.

malicious input (or a mistake) can result in arbitrary code
execution. (think rm -R /)


gnari

 

[gnari]

That would result in evaling "rm ..R /". ;-)

lots of destructive commands do not include a '-'.
in any case , there is no /g in your code, so this
limitation can easily be avoided.

system("ls -;rm -R /")

gnari

 

[Noname]

Path:
news2.nokia.com!news1.nokia.com!news2.nokia.com.POSTED!not-for-mail
Newsgroups: comp.lang.perl.misc
Subject: Expression Problem
From: Noname <[email protected]>
User-Agent: Xnews/5.04.25
Lines: 5
Message-ID: <Wc%[email protected]>
Date: Tue, 10 Aug 2004 07:56:38 GMT
NNTP-Posting-Host: 172.21.11.70
X-Complaints-To: (e-mail address removed)
X-Trace: news2.nokia.com 1092124598 172.21.11.70 (Tue, 10 Aug 2004
10:56:38 EET DST) NNTP-Posting-Date: Tue, 10 Aug 2004 10:56:38 EET DST
Organization: Nokia
Xref: news1.nokia.com comp.lang.perl.misc:285995

Hi,
I have input from STDIN like $Input="1-5,6,8,10-15";
which actually needs to be interpreted as an
array=1,2,3,4,5,6,8,10,11,12,13,14,15
how can it be done,

I did had a bad experience with "eval" function so I will surely aviod it ,
and use the one without it ,
thanks for your time and information

 

[gnari]

[...]

lots of destructive commands do not include a '-'.

I think you took my reply too seriously.

that was on purpose

anyways, the OP seems to have been aware of the
dangers of indiscriminate eval(), so all's well.

gnari

 

[510046470588-0001]

please do not do this unless you trust the input 100% to
be in the format described.

malicious input (or a mistake) can result in arbitrary code
execution. (think rm -R /)

use the Safe module judiciously

Klaus Schilling

 

[Jay Tilton]

: Hi,
: I have input from STDIN like $Input="1-5,6,8,10-15";
: which actually needs to be interpreted as an
: array=1,2,3,4,5,6,8,10,11,12,13,14,15
: how can it be done,

use Set::IntSpan;
my @array = Set::IntSpan ->new( $Input ) ->elements;