PHP string replacement function can replace multiple keywords at the same time

/**
* String replacement function
* edit: bbs.it-home.org
*/
function replace($string,$keyArray,$replacement,$i){
 $result='';
 if($i<(count ($keyArray))){
 $strSegArray=explode($keyArray[$i],$string);
 foreach ($strSegArray as $index=>$strSeg){
 $x=$i+1;
 if ($index==(count($strSegArray)-1))
 $result=$result.replace($strSeg,$keyArray,$replacement,$x);
 else
 $result=$result.replace($strSeg ,$keyArray,$replacement,$x).$replacement[$i];
 }
 return $result;
 }
 else{
 return $string;
 }
}

Code description: $string=' key name array can contain both integer and string type key names, 12345678 because PHP does not actually distinguish between index arrays and associative arrays. If no key is specified for the given value, the current largest integer index value is taken, and the new key name will be that value plus one. If the specified key name already has a value, the value will be overwritten. '; Example:

$keyArray=array('array','integer','2345','key name');
$replacement=array('AAAA','BBBB','CCCC','DDDD' );
echo replace($string,$keyArray,$replacement,0);