How to get which character appears most often in a string

Reprint address: http://blog.qita.in/?post=467

$str=”asdfgfdas323344##$$fdsdfg*$**$*$**$$443563536254fas”;//Any length string

//Solution one (the fastest solution, but the basic skills must be solid )
$arr=str_split($str);
$arr=array_count_values($arr);
arsort($arr);
print_r($arr);

//Solution 2 (certain requirements for logical ability)
 $arr=str_split($str);
$con=array();
foreach ($arr as $v){
if (!@$con[$v]){
@$con[$v]=1 ;
}else{
@$con[$v]++;
}
}
arsort($con);
print_r($con);
//Solution 3
$arr=str_split($str);
 $unique=array_unique($arr);
foreach ($unique as $a){
$arr2[$a]=substr_count($str, $a);
}
arsort($arr2);
print_r($arr2 );