PHP code to calculate the most frequent characters in a string of unknown length

$arr=str_split($str);
$arr=array_count_values($arr);
arsort($arr);
print_r($arr);
?>

Output: Array ( [$] => 7 [3] => 6

=> 6 [4] => 5 [f] => 5 => 4 [d] => 4 [5] => 3 [a] => 3 [6] => 2 [2] => 2 [g] => 2 [#] => 2 )

Method 2: Functions used: array_unique: Remove duplicate values ​​from the array. substr_count: Count the number of times a substring appears in a string.

$str="asdfgfdas323344##$$fdsdfg*$**$*$**$$443563536254fas";//Any length string
$arr=str_split($str );
$unique=array_unique($arr);
foreach ($unique as $a){
$arr2[$a]=substr_count($str, $a);
}
arsort($arr2);
print_r ($arr2);
?>