On Thu, Aug 18, 2016 at 9:39 PM <kp...@freenet.de> wrote: > Hello, > > What's the better way to decide if an element exists in an array? > Something like what ruby does, > > irb(main):001:0> x=[3,1,4,2,9,0] > => [3, 1, 4, 2, 9, 0] > irb(main):002:0> x.include? 4 > => true > irb(main):003:0> x.include? 10 > => false > irb(main):004:0> quit > > > I tried searching but found nothing such a method in perl.
The grep builtin does what you want perldoc -f grep http://perldoc.perl.org/functions/grep.html my $found = grep { $_ == 4 } (3, 1, 4, 2, 9, 0); # 1 my $not_found = grep { $_ == 10 } (3, 1, 4, 2, 9, 0); # 0 The return value for grep in scalar context is the number of times it matches. In list context, it returns all of the elements that match: my @found = grep { $_ % 2 } (3, 1, 4, 2, 9, 0); # @found holds (3, 1, 9) The any function from List::Util will also do what you want. perldoc List::Util http://perldoc.perl.org/List/Util.html#any my $found = any { $_ == 4 } (3, 1, 4, 2, 9, 0); # true my $not_found = any { $_ == 10 } (3, 1, 4, 2, 9, 0); # false Which you want depends on the application. The grep function will return a number between 0 and the size of the list and reads the entire list. The any function returns the canonical true (a tri-value that holds "1", 1, and 1.0) or false (a tri-value that holds "", 0, 0.0) values and stops at the first matching value. The canonical false value often throws people for a loop as they expect it to be "0" in string context, but it is "". You may want to say my $found = (any { $_ == 10 } (3, 1, 4, 2, 9, 0)) || 0; to force it to be 0 instead of the canonical false value.
