$_ = 'I threw the balls through the rings and won a prize!';
print "Gotcha!\n" if /^(?=.*balls)(?=.*rings)/s;
[download]

If you want to match another substring, you can just add another lookahead assertion.

I recall that I picked this one up from Abigail.

if ($line =~ m/balls/ and $line =~ m/rings/) {
  # ...
}
[download]

This can be done with one regex, too, but it's much more complicated (and probably slower) and more difficult to maintain, for example:

update: A better technique to combine the two regexes into one is presented in chipmunk's reply to this node. It's not only more maintainable, but it's probably faster then my regex here, at least.

update 2: I have benchmarked my combined regex, chipmunk's regex, and just using two regexes. (All tuned for matching "rings" and "balls" of course.) Using two regexes is signigantly faster (by 30% for the string "ringsballs" with that factor getting much larger the longer the searched string is.) My combined regex tends to be the slowest of them all, and chipmunk's comes in second. (though performance was close to my combined regex when the string being searched started with one of the strings "rings" or "balls" and there was a lot of junk text in the string being matched.)

(The benchmark was performed on strings composed of a number of random characters, followed by "rings" followed by a number of random characters followed by "balls" followed by a number of random characters, and the same without the first set of random characters. Random characters were all selected from lowercase letters a through z.)

#!/usr/bin/perl -wT
use strict;

my $line = "I like 'balls' and 'rings', do you like 'rings' and 'balls
+'?";
print "Before = $line\n";
$line =~ s/(balls|rings)//g;
print "After  = $line\n";

=output
Before = I like 'balls' and 'rings', do you like 'rings' and 'balls'?
After  = I like '' and '', do you like '' and ''?
[download]

Update: Apparently the question is an AND one, not an OR one (which is what I provided an answer to). In general, I think mutiple regexes are best for this sort of thing. i.e. if (/balls/ && /rings/) { } there are tricky ways of doing this in one regex, but they tend to be slower, and less readable.

-Blake

You want alternation to match one of two or more words, m/(balls)|(rings)/.

Update: Phooey, balls AND rings.

m/balls/ && m/rings/ && your_action();
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After Compline,
Zaxo

my @patterns = (qr/balls/, qw/rings/);
my @file = <IN_FILE>;
my @to_print;
foreach my $line (@file) {
    push @to_print, $line unless grep { $line =~ /$_/ }  @patterns;
}
print OUT_FILE @to_print;
[download]

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