小弟我有有关问题

我有问题求助
刚接触PHP ,写了如下的一小段，$x->name();为什么打印出来是空啊？

PHP code

interface man{    function talk();}abstract class person{    abstract function name();    abstract function age();    var $c="这是一个抽象类
";}class xiaoming extends person implements man {    function name(){        echo ("xiaoming
");    }    function age(){        echo ("12"."
");    }    function talk(){        echo ("love
");    }}class xiaoli extends person implements man{    var $mingzi;    function _construct($mingzi){        $this->mingzi=$mingzi;    }    function name(){        echo ($this->mingzi."
");    }    function age(){        echo ("13
");    }    function talk(){        echo ("you");    }}$p = new xiaoming();$p->name();$p->age();$p->talk();$x = new xiaoli("xiaoli");$x->age();$x->name();$x->talk();