一、给二维数组添加元素

错误做法：

foreach ($myaddr  as $k=>$line){
$line['str'] = $line['province'].$line['city'].$line['county'].$line['address'];
}

错误原因：$k和$line在foreach里面是虚拟变量

正确做法1：

foreach ($myaddr as $k=>$line){

$myaddr[$k]['str'] = $myaddr[$k]['province'].$myaddr[$k]['city'].$myaddr[$k]['county'].$myaddr[$k]['address'];

}

正确做法2：给$line添加引用符号&

foreach ($myaddr as &$line){

$line['str'] = $line['province'].$line['city'].$line['county'].$line['address'];

}