当索引处的值是对象时，在PHP中处理未定义的偏移量警告

Question

I have a code like this:

class PlayerList{
    public static $player_list= array();
    //other functions
    function getPlayer($playerNumber){

           if(isset((self::$player_list[$playerNumber])))
              return self::$player_list[$playerNumber];
            else
              return NULL;
      }

This function getPlayer($playerNumber) should return the player object in the static array $player_list indexed using the given $playerNumber. It works when the index exists else throws an undefined offset. The index is an important attribute of objects of Player class, so re-ordering the array is out of question.

Now, in the calling part:

$players=new PlayerList();
$playerNumber=readline("

Enter player number:");
$player=$players->getPlayer($playerNumber); 

if(//valid player){
//code
}
else{
//code
}

How do i check if the indexed player exists or not,and if not, return null, in the getPlayer function itself, and prevent PHP from giving undefined offset notice?

Answer 1

As you are returning NULL when you cannot find a player, simply test for NULL using isset()

$player=$players->getPlayer($playerNumber); 
if ( isset($player) ) { 
    // Player exists
}else{
    // Player Does NOT exists
}

In fact you could probably get away with a simple

$player=$players->getPlayer($playerNumber); 
if ( $player ) { 
    // Player exists
}else{
    // Player Does NOT exists
}