I attempted to find a quicker way to access each char in string. I tested two methods. One is to split into an array, and the other way is to substr.
I have tested these two methods. It seems that foreach() is significantly more quickly, but split// costs too much time. 
my $string='aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaaaaaaaaaaa';
my @chars=split //,$string;

timethese(50000,{
    'Substr'=>sub{
        my $string='aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaaaaaaaaaaaaaaaaaaa';
        for (my $i=0;$i<length $string; $i++) {
            my $char=substr $string,$i,1;
        }
    },
    'pre_splitted'=>sub{
        foreach my $char (@chars) {
        
        }
    },
    'Split'=>sub{
        my @string=split //,'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa';
        foreach my $char (@string) {
            
        }
    }
});

[download]
split: 4826/s
substr: 18214/s
pre-splitted, only foreach in benchmark: 78247/s

So, is there any quicker way to iterate chars?

In reply to How to access each char in a string most quickly? by llancet

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