PHP foreach通过一系列对象

Question

I'm trying to use a foreach loop for an array of objects. Inside of the BeginBattle() method I want to iterate through all of the objects and increment their played count automatically. Unfortunately, the web browser shows I have an error: Fatal error: Call to a member function BattleInitiated() on a non-object in /nfs/c05/h01/mnt/70299/domains/munchkinparty.neededspace.net/html/Battle.php on line 75

Any ideas?

<?php
/* 
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 * Description of Battle
 *
 * @author joshualowry
 */
class Battle {
    /**
     *
     * @var <type>
     */
    private $_players;
    /**
     *
     * @var <type>
     */
    private $_battleInProgress;
    /**
     *
     */
    public function Battle(){
        $this->_players = array();
        $this->_battleInProgress = FALSE;

    }
    /**
     *
     * @param <type> $player
     * @return <type>
     */
    public function AddPlayer($player){
        if(!$this->_battleInProgress)
            $this->_players[] = $player;
        else
            return;
            //Spit some error
    }

    /**
     *
     * @param <type> $player
     * @return <type>
     */
    public function BattleWon($player){
        if($player != NULL)
            $player->BattleWon();
        else
            return;
            //Spit some error
    }
    /** GetPlayerByName Get the player's object by the player's name field.
     *
     * @param <type> $playerName
     * @return <type>
     */
    public function GetPlayerByName($playerName){
        foreach($this->_players as &$player) {
            if($player->GetName() == $playerName)
        return $player;
        }
        return NULL;
    }

    /**
     *
     */
    public function BeginBattle(){
        $this->_battleInProgress = TRUE;
        foreach($this->_players as $player){
        $player->BattleInitiated();
    }
    }
    /**
     *
     */
    public function DisplayCurrentBoard() {
        echo "Name  Alias   Wins    Battles<br/>";
        foreach($this->_players as &$player){
            echo "$player->GetName()    $player->GetAlias() $player->GetWins()  $player->GetBattles()<br/>";
        }
    }

}
?>

This is where everything is declared and called:

<?php
    include 'Battle.php';
    include 'Person.php';
    include 'Player.php';

    $currentBattle = new Battle();

    $playerA = new Player("JohnnyDanger","John",0,0);
    $playerB = new Player("JoshTheJest","Josh",0,0);
    $PlayerC = new Player("CarbQueen","Nicole",0,0);

    $currentBattle->AddPlayer($playerA);
    $currentBattle->AddPlayer($playerB);
    $currentBattle->AddPlayer($playerC);

    $currentBattle->BeginBattle();
    $currentBattle->BattleWon($currentBattle->GetPlayerByName("Josh"));
    $currentBattle->DisplayCurrentBoard();
?>

The Player Class

    <?php

    /**
    * Description of Player
    *
    * @author joshualowry
    */
    class Player extends Person {

        private $_alias;
        private $_wins;
        private $_battles;

        public function Player($name, $alias, $wins, $battles) {
            parent::SetName($name);
            $this->_alias = $alias;
            $this->_battles = $battles;

            if($battles == 0) {
                $this->_wins = 0;
            }
            else {
                $this->_wins = $wins;
            }
        }

        protected function SetAlias($value){
            $this->_alias = $value;
        }

        public function GetAlias(){
            return $this->_alias;
        }

        protected function SetBattles($value) {
            $this->_battles = $value;
        }

        public function GetBattles(){
            return $this->_battles;
        }

        protected function SetWins($value) {
            $this->_wins = $value;
        }

        public function GetWins() {
            return $this->_wins;
        }

        public function BattleWon(){
            $this->_wins += 1;
        }

        public function BattleInitiated(){
            $this->_battles += 1;
        }

    }

?>

Answer 1

The error message indicates that you are trying to all the BattleInitiated() method on something that wasn't an object.

Judging from your code, the problem seems to be with this loop, in the BeginBattle() method :

foreach($this->_players as $player){
    $player->BattleInitiated();
}

Which means $player, at least one in your array, is probably not an object ; maybe it's null , or an array ?

To know more, you should use var_dump to display the content of $this->_players before the loop, just to make sure it contains what you expect it to :

public function BeginBattle(){
    var_dump($this->_players);
    $this->_battleInProgress = TRUE;
    foreach($this->_players as $player){
        $player->BattleInitiated();
    }
}

If $this->_players doesn't contain what you expect it to (and it probably doesn't !) , you'll then have to find out why...

Considering $this->_players is modified by the AddPlayer() method, which adds what it receives to the end of the array, I would bet that AddPlayer() is called at least once without a correct $player as a parameter.

To help with that, you could use var_dump on the $player being added :

public function AddPlayer($player){
    var_dump($player);
    if(!$this->_battleInProgress)
        $this->_players[] = $player;
    else
        return;
        //Spit some error
}

If that var_dump indicates at least once that $player is not an object (for instance, it's null , or an array, or a string, ...) , that's the cause of your Fatal Error.

Answer 2

don't you see it??

it's all because of a small typo:

 $playerA = new Player("JohnnyDanger","John",0,0);
    $playerB = new Player("JoshTheJest","Josh",0,0);
    $PlayerC = new Player("CarbQueen","Nicole",0,0);

    $currentBattle->AddPlayer($playerA);
    $currentBattle->AddPlayer($playerB);
    $currentBattle->AddPlayer($playerC);

declared: $_P_layerC used: $_p_layerC

correct that and you're good to go

Answer 3

Your $player variable is either null or not an Object of the type you want it to be.

PlayerObject is what ever your class name for player is.

For example

$battle=new Battle();
$player1=new PlayerObject();
$player2="player";
$battle->AddPlayer($player1);
$battle->AddPlayer($player2);
$battle->BeginBattle();

when you call BeginBattle() the $player1->BattleInitiated(); will be successful but the $player2->BattleInitiated() will give you the fatal error and stop your code from running. same if $player2 was null, an integer or something that is not PlayerObject .