Perl在参数中找到奇数

Question

Example:

./odd.pl a a b b b

output:

b b b

find a odd number argument and print

I tried:

my %count;
foreach $arg (@ARGV) {
    $count{$arg}++;
    if ($count{$arg} % 2 eq 1) { print "$arg"; }
}

print "\n";

Answer 1

It looks like you want to print the values that appear an odd number of times.

The problem with your attempt is that you check the counts before you finish obtaining the count of the different values!

Solution:

my %counts;
for my $arg (@ARGV) {
    ++$counts{$arg};
}

my @matches;
for my $arg (@ARGV) {
    if ($counts{$arg} % 2 == 1) {
        push @matches, $arg;
    }
}

print("@matches\n");

Note that I changed eq to == because eq is for string comparisons.

Simplified solution:

my %counts;
++$counts{$_} for @ARGV;
my @matches = grep { $counts{$_} % 2 } @ARGV;
print("@matches\n");