How can i extract a number from an string

[Sombrerero_loco]

Hi monkers! I need to do the next and really, i dont know how. I need to from the $variable that contains the next strings (from an array foreach) BS0-bleble, BS1-bleble, BS2-bleble, BS3-bleble, BS4-bleble and BS5-bleble.. Extract the number and compare (to do the comparison its done) but to split the number from the string, i dont know. I know i must to first of all an split to stract the BSx- from the bleble, im doing that like this:

foreach $var1 (@array) {
($hierarchie,$trash)= split('-',$var1);

}

But i dont know how i should do to split the number from the BSx (from 0 to 5) in another variable. Thanks monks!

[Bloodnok]

foreach (@array) {
    /^BS(\d)/;
    my $num = $1;
    .
    .
}

[jplindstrom]

/^BS(\d)/ or warn("Invalid frobniz id ($_)\n"), next;

Or possibly die on bad input. Never ignore it.

(And, it's better to be explicit about the loop variable IMHO, $_ is a missed opportunity to write self documented code).

/J

[Sombrerero_loco]

and this should capture only the number from the string "BS4-SuchaString" ???

[Bloodnok]

As the RE says, if the string begins with BS and is followed by a single digit, that digit will be captured - see perlre.

[gone2015]

Consider a regular expression. There is also the Perl regular expressions quick start and the tutorial. If you are going to mess about with Perl, you ought to get to grips with regular expressions.

In particular, consider a regular expression using a "capture". (Update: as demonstrated by some quicker monks.)

[JavaFan]

my ($number) = $var1 =~ /([0-9]+)/;   # Or
my $number = substr $var1, 2, 1;

[setebos]

split will work only on one digit number:

(split(//,"BS0-bleble"))[2]

[JavaFan]

Not if you know split:

$ perl -wE 'say +(split/([0-9]+)/,"BS123-bleble")[1]'
123

[johngg]

An alternative to JavaFan's use of a capture in the split regexp could be to use look-arounds to do the split at points where the string changes from non-digit to digit and vice-versa. I think JavaFan's method is better in this case but the look-arounds can sometimes be a useful technique.

$ perl -le '
> $_ = q{BS123-bleble};
> print +( split m{(?x) (?: (?<=\D)(?=\d) | (?<=\d)(?=\D) )} )[ 1 ];'
123
$

I hope this is of interest.

Cheers,

JohnGG

[Sombrerero_loco]

Wow....such complicate to extract the number. I never think its takes too many code to extract just a number, i thought using split the code must be easier. I'll try it today and keep you posted.. Thanks everyone for the replies!