PHP에서 루프 점프에 대한 질문

//php当前循环为1，循环由里到外依次递增，break默认为1，例如跳出第2层循环
for ($i=0;$i<3;$i  ){
    foreach (array(1,2,3) as $val){
        foreach (array(1,2,3) as $val){
            echo "1层循环";
            break 2;  //跳出第2层循环
        }
        echo "2层循环";
    }
    echo "3层循环";
}
//结果：
//1层循环
//3层循环
//1层循环
//3层循环
//1层循环
//3层循环
?>