本文实例讲述了php随机抽奖用法。分享给大家供大家参考。具体分析如下：
1. 按照设定的概率，得到随机抽奖的结果。
代码如下:
/**
 * 抽奖工具
 */
class lottery_tool {
    protected static $awardsarr;
    protected static $profield = 'probability';
    protected static $prosum = 0;
    protected static $checkaward = false;
    const success_code = 0;
    const fail_code = -1;
    //检查抽奖数据
    protected static function checkawards(){
        if (!is_array(self::$awardsarr) || empty(self::$awardsarr)) {
            return self::$checkaward = false;
        }
        self::$prosum = 0;
        foreach (self::$awardsarr as $_key => $award) {
            self::$prosum += $award[self::$profield];
        }
        if (empty(self::$prosum)) {
            return self::$checkaward = false;
        }
        return self::$checkaward = true;
    }
    protected static function successroll($rollkey){
        return array('code' => self::success_code, 'roll_key' => $rollkey, 'msg' => 'roll success');
    }
    protected static function failroll($msg = 'roll fail'){
        return array('code' => self::fail_code, 'msg' => $msg );
    }
    //抽奖
    public static function roll () {
        if (false == self::$checkaward) {
            return self::failroll('awards data is not the right format!');
        }
        $result = mt_rand(0, self::$prosum);
        $provalue = 0;
        foreach (self::$awardsarr as $_key => $value) {
            $provalue += $value[self::$profield];
            if ($result                 return self::successroll($_key);
            }
        }
        return self::failroll('wrong');
    }
    //改变概率字段名
    public static function setprofield($field = null) {
        if (!empty($field)) {
            self::$profield = $field;
        }
    }
    //设置奖品
    public static function setawards($awards){
        self::$awardsarr = $awards;
        self::checkawards();
    }
}
2. 示例代码：
代码如下:
$awards = array(
    '0' => array('pro' => 15, 'info' => '15%的可能性'),
    '1' => array('pro' => 25, 'info' => '25%的可能性'),
    '2' => array('pro' => 40, 'info' => '40%的可能性'),
    '3' => array('pro' => 20, 'info' => '20%的可能性'),
    );
lottery_tool::setprofield('pro');
lottery_tool::setawards($awards);
$result = array();
for ($i = 10000; $i --;) {
    $result[] = lottery_tool::roll();
}
foreach ($result as $key => $value) {
    $awards[$value['roll_key']]['num'] ++;
}
echo '
';
var_dump($awards);运行结果如下：
代码如下:
array
  0 =>
    array
      'pro' => int 15
      'info' => string '15%的可能性' (length=15)
      'num' => int 1596
  1 =>
    array
      'pro' => int 25
      'info' => string '25%的可能性' (length=15)
      'num' => int 2484
  2 =>
    array
      'pro' => int 40
      'info' => string '40%的可能性' (length=15)
      'num' => int 3939
  3 =>
    array
      'pro' => int 20
      'info' => string '20%的可能性' (length=15)
      'num' => int 1981
希望本文所述对大家的php程序设计有所帮助。