counting characters

[celavek via Digitalmars-d-learn]

On Tuesday, 19 July 2016 at 09:41:32 UTC, John wrote:
> On Tuesday, 19 July 2016 at 09:34:11 UTC, celavek wrote:
>> Hi,
>>
>> I am trying to count characters in a string like:
>>
>> const string dna_chain = 
>> "AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC";
>> counts['A'] = countchars!(dna_chain, 'A');
>
> countchars(dna_chain, "A");

Not working. Same error.