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sqspat has asked for the wisdom of the Perl Monks concerning the following question:
Hello All,
I am trying to find the most efficient way of searching through an array for the value 0 and if it finds a zero it should break out of the search and print a Fail to the test I am running.
I found out the hard way that it is not possible to do a pattern match with an array as below because it does not iterate through the elements; ... doooh !!!
any suggestions?
my @results_file=(1,1,1,0,1);
if (@results_file =~ m/0/)
{
print"\n--FAIL--";
}
else
{
print "\n--PASS--STATUS\n";
print "\n@results_file\n";
}
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Re: Most efficient way of search elements in an array
by Corion (Patriarch) on Sep 15, 2009 at 14:06 UTC
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So close, yet so far :)
If you're using Perl 5.10, you can use the "Smartmatch Operator" ~~ instead of =~ and your program will work:
use strict;
for my $testcase ([1,1,1,0,1],[1,1,1,1,1],[1,10,101]) {
my @results_file = @$testcase;
if (@results_file ~~ m/0/)
{
print"\n--FAIL-- @results_file";
}
else
{
print "\n--PASS--STATUS\n";
print "\n@results_file\n";
}
}
The only relevant change is from @results_file =~ /0/ to @results_file ~~ /0/.
You might want to consider anchoring your match, so you match only a 0, and not 100, or 101. | [reply]
[d/l]
[select] |
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But Smartmatch is smart enough to match on numeric equality:
>perl -wMstrict -le
"for my $ar (
[1, 1, 0, 1], [0], [0, 0, 0],
[qw(0)], [qw(00)], [qw(000)], [qw(1 1 0 1)],
[1], [], [1, 10, 01, 101, 010],
[qw(1 10 01 101 010)],
) {
print qq{(@$ar): }, @$ar ~~ 0 ? 'naught' : 'not'
}
"
(1 1 0 1): naught
(0): naught
(0 0 0): naught
(0): naught
(00): naught
(000): naught
(1 1 0 1): naught
(1): not
(): not
(1 10 1 101 8): not
(1 10 01 101 010): not
Update: Added 'numeric string' test cases. | [reply]
[d/l] |
Re: Most efficient way of search elements in an array
by toolic (Bishop) on Sep 15, 2009 at 14:18 UTC
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Use a for loop to cycle through your array elements,
and break out of the loop as soon as 0 is found using last:
use strict;
use warnings;
my @results_file = (1,1,1,0,1);
for (@results_file) {
if (/0/) {
print "\n--FAIL--\n";
last;
}
else {
print "\n--PASS--STATUS\n";
print "\n$_\n";
}
}
__END__
--PASS--STATUS
1
--PASS--STATUS
1
--PASS--STATUS
1
--FAIL--
Update: Or maybe this is the output you were looking for...
use strict;
use warnings;
my @results_file = (1,1,1,0,1);
my $pass = 1;
for (@results_file) {
if (/0/) {
print "\n--FAIL--\n";
$pass = 0;
last;
}
}
if ($pass) {
print "\n--PASS--STATUS\n";
print "\n@results_file\n";
}
__END__
--FAIL--
| [reply]
[d/l]
[select] |
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This does it alright ... except I just want one PASS to be printed if the script determines that all the array elements are 1
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[d/l] |
Re: Most efficient way of search elements in an array
by Fletch (Bishop) on Sep 15, 2009 at 14:10 UTC
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[d/l] |
Re: Most efficient way of search elements in an array
by whakka (Hermit) on Sep 15, 2009 at 14:58 UTC
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use Test::More tests => 2;
my @not_ok = (1,1,1,0,1);
my @ok = (1,1,1,1,1,1);
ok( not (grep { $_ == 0 } @$_), 'No zeros' )
for ( \@not_ok, \@ok );
| [reply]
[d/l] |
Re: Most efficient way of search elements in an array
by Marshall (Canon) on Sep 15, 2009 at 19:49 UTC
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I don't see the need for super efficiency for an array with 5 or 10 True/False values. Use the scalar value of grep to count the number of "zeroes".
#!/usr/bin/perl -w
use strict;
my @results_file=(1,1,1,0,1);
print "at least one zero" if (grep{/0/}@results_file);
__END__
prints:
at least one zero
numeric compare in the grep will do the same thing:
print "at least one zero" if (grep {$_ == 0}@results_file);
Slight modification to your code yields the following.... The grep says "tell me the number of times that '0'(zero) was seen when I looked at all elements of @results_file". Yes, there are ways to "stop counting" when the first "zero" is reached, but for just a couple of dozen things in @results_file, it just won't matter.
#!/usr/bin/perl -w
use strict;
my @results_file=(1,1,1,0,1);
if (grep {/0/}@results_file ) #if (grep {$_ == 0}@results_file)
#numeric value
{
print"\n--FAIL--";
}
else
{
print "\n--PASS--STATUS\n";
print "\n@results_file\n";
}
| [reply]
[d/l]
[select] |
Re: Most efficient way of search elements in an array
by ccn (Vicar) on Sep 15, 2009 at 20:04 UTC
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