Determine repeat characters in a php string

Question

I have found many examples of how to find repeat characters in a string. I believe my requirement is unique.

I have string

$string=aabbbccffffd;
         


        

Answer 1

Based on georg's great point, I would use a regex. This will handle split duplicates like ddaaffffd with array keys dd=>2 and ffffd=>3 but will only show one entry for dd when given ddaadd. To represent both would require a more complex array:

$string = "ddaabbbccffffda";
preg_match_all('/(.)\1+/', $string, $matches);
$result = array_combine($matches[0], array_map('strlen', $matches[0]));
arsort($result);

If you only need a count of ALL occurrences try:

$result = array_count_values(str_split($string));
arsort($result);

Legacy Answers:

If you don't have split duplicates:

$string  = 'aabbbccffffd';
$letters = str_split($string);
$result  = array_fill_keys($letters, 1);
$previous = '';

foreach($letters as $letter) {
    if($letter == $previous) {
        $result[$letter]++;
    }
    $previous = $letter;
}
arsort($result);
print_r($result);

Or for a regex approach:

preg_match_all('/(.)\1+/', $string, $matches);
$result = array_combine($matches[1], array_map('strlen', $matches[0]));
arsort($result);