How to get the first non-repeating character in the character stream in PHP

This article explains how PHP obtains the first non-repeating character in the character stream.

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 the index array

Implementation code

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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