如何查找仅在字符串中出现一次的数字？

Question

Let's say I have input string

String 1 : 1234123
String 2 : 76523752

From those string, I'd like to know which numbers that only appears once. So in my case the output should be

String 1 : array(4)
String 2 : array(6,3)

I'm guessing I'll use strpos() for this task but I couldn't get any logical flow to make this happen. Can you help me figure this out?

Answer 1

Boring solution but it works!

$string="1234123";
$result=array();
foreach (count_chars($string, 1) as $i => $val) {
     if($val==1) $result[]=chr($i);
}
print_r($result);