PHP gets the first non-repeating character in the character stream

This article mainly introduces the method of PHP to obtain the first non-repeating character in the character stream, involving PHP's operation skills related to traversing and judging index arrays. Friends in need can refer to it. I hope it can help everyone.

Please implement a function to find the first character that appears only once in the character stream. For example, when reading only the first two characters "go" from the character stream, the first character that appears only once is "g". When the first six characters "google" are read from this character stream, the first character that appears only once is "l".
Output description:
If there is no character that appears once in the current character stream, return # characters

Solution

Use index Array

Implementation code

<?php
global $result;
//Init module if you need
function Init(){
  global $result;
  $result = [];
}
//Insert one char from stringstream
function Insert($ch)
{
  global $result;
  // write code here
  if(isset($result[$ch])){
    $result[$ch]++;
  }else{
    $result[$ch] =1; 
  }
}
//return the first appearence once char in current stringstream
function FirstAppearingOnce()
{
  global $result;
  foreach($result as $k =>$v){
    if($v ==1){
      return $k;
    }
  }
  return "#";
}

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