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

Here's exactly what your looking for :

<?php
function printCharMostRepeated($str)
{
    if (!empty($str))
    {
        $max = 0;
        foreach (count_chars($str, 1) as $key => $val)
            if ($max < $val) {
                $max = $val;
                $i = 0;
                unset($letter);
                $letter[$i++] = chr($key);
            } else if ($max == $val)
                $letter[$i++] = chr($key);
        if (count($letter) === 1)
            echo 'The character the most repeated is "'.$letter[0].'"';
        else if (count($letter) > 1) {
            echo 'The characters the most repeated are : ';
            $count = count($letter);
            foreach ($letter as $key => $value) {
                echo '"'.$value.'"';
                echo ($key === $count - 1) ? '.': ', ';
            }
        }
    } else
        echo 'value passed to '.__FUNCTION__.' can\'t be empty';
}

$str  = 'ddaabbccccsdfefffffqqqqqqffffdaaa';
printCharMostRepeated($str);

Answer 2

<?php
  $word = "abcdefghbi";

  for($i=0; $i<strlen($word);$i++){
      for($k=0;$k<strlen($word);$k++){
          if($word[$i] == $word[$k] && $i != $k){
              echo $word[$k]." is duplicate"; 
              exit;     
          }
    
      }
  }
  echo "no match found";
?>

Answer 3

use count-chars()

http://php.net/manual/en/function.count-chars.php

and then asort()

http://php.net/manual/en/function.asort.php

Answer 4

$data = "aabbbcccffffdz";
$array = str_split($data);
$v = array_count_values($array);
foreach($v as $k => $val){ 
        echo $k.' = '.$val.'<br>';
}

Answer 5

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);