PHP interview question: How to know which character appears most often in a string of unknown length? (Strings can be composed of letters, numbers and other characters) Please write the code. _PHP Tutorial

php interview question: How to know which character appears most often in a string of unknown length? (Strings can be composed of letters, numbers and other characters) Please write the code.

How to know which character appears most often in a string of unknown length? (Strings can be composed of letters, numbers and other characters) Please write the code.


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

//Solution 1 (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 (requires certain logic 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);