如何计算Perl数组中特定字母的数量？

Question

I have an array which only has letters in it, no digits. I want to count the number of times a specific letter shows. I don't want to use a hash, i need to preserve the order of the list.

use strict;
use warnings;

my %counts;
$counts{$_}++ for @array;
print "$counts\n";

Answer 1

The code that you have seems to work find for counting the occurrences. The only problem you have is in displaying the counts. You're using a new scalar variable called $counts which is undeclared and empty.

What you want is this:

use strict;
use warnings;

my %counts;
$counts{$_}++ for @array;
print "$_: $counts{$_}\n" for keys %counts;

Answer 2

Use grep for to do it

my @ar = qw(abc cde fgh 123 abc);
my $count = grep{ /ab/} @ar;
print $count;

Or else use foreach

my @ar = qw(abc cde fgh 123 abc);
my $m;
$m+= /ab/,foreach (@ar);
print $m;

While the match was encountered $m will increment.

Answer 3

您可以考虑在CPAN上使用Text :: CountString模块。