如何在Perl中将字符串转换为字符串数组？

Question

I am attempting to write a script that will take both a string and a single character from the command line, and then search the string for the single character for the number of occurrences. I have attempted to do this by making the string into an array and looping through each individual element of the array, but I get 0 every time I try to do this. Is converting the string to the array of single characters possible or should I try a new method?

use strict;
use warnings;    
if ($ARGV[0] eq '' or $ARGV[1] eq '') {
        print "Usage: pe06f.pl string char-to-find\n";
        exit 1;
}
my $string = $ARGV[0];
my $searchChar = $ARGV[1];
if (length($searchChar) > 1) {
        print "Second argument should be a single character\n";
        exit 2;
}
my @stringArray = split /\./,$string;
my $count = 0;
$i = 0;
for ( $i=0; $i <= length($stringArray); $i++) {
        if ( $stringArray[$i] eq $searchChar) {
                print "found $b at position $i";
                $count++;
        }
}
print "found $count occurrences of $searchChar in $string\n";

Answer 1

You could try this:

#!/usr/bin/perl

use warnings;
use strict;

my ($str, $chr) = @ARGV;

my $cnt = () = $str =~ m/$chr/g;
print "$cnt\n";

---

Explanation:

$cnt = () = $str =~ m/$chr/g will find out how many matches of character $chr there are in string $str , here is how it achieves that:

1. $str =~ m/$chr/g will do a global pattern matching ( /g ), and
2. () = ... will put that pattern matching in list context,
3. therefore it will return a list of all the matched strings,
4. finally the $cnt = ... will put that list in scalar context,
5. so the value of $cnt will be the number of element in that list.