php foreach如何跳出两层循环(详解)

    $arr1 = array('a1','a2','a3','a4');
    $arr2 = array('b1','b2','b3','b4');
    foreach($arr1 as $a1){
      foreach($arr2 as $k=>$a2){
        if($k=='2'){
          break 2;
        }
        echo $a1.'==='.$a2.'<br/>';
      }
    }