PHP development classification technology drop-down menu classification (3)

We customize a function displayCate to add the

<selsct> style to the looped getList to output the drop-down menu, similar to the following:

| -- Clothing

|-- Men's clothing

|-- Women's clothing

|-- Food

## |-- Staple food

|-- Rice

|-- Non-staple food

<?php
function displayCate($pid=0,$selected=1){
  $rs=getList($pid);
  $str='';
  $str.="<select name='cate'>";
  foreach ($rs as $key=>$val){
    $selectedstr='';
    if ($val['id'] == $selected){
      $selectedstr="selected";
    }
    $str.="<option {$selectedstr}>{$val['title']}</option>";
  }
  return $str.="</select>";
}
echo displayCate(0,3);
?>

<?php
header("content-type:text/html;charset=utf8");

$link = mysqli_connect('localhost','username','password','test');
mysqli_set_charset($link, "utf8");
if (!$link) {
  die("连接失败:".mysqli_connect_error());
}

function getList($pid=0,&$result=array(),$space=0){
  global $link;
  $space=$space+2;
  $sql="select * from class where pid = $pid";
  $res = mysqli_query($link,$sql);
  while ($row = mysqli_fetch_assoc($res)){
    $row['title']=str_repeat('&nbsp;',$space).'|-- '.$row['title'];
    $result[]=$row;
    getList($row['id'],$result,$space);
  }
  return $result;
}
$rs=getList();
print_r($rs);

function displayCate($pid=0,$selected=1){
  $rs=getList($pid);
  $str='';
  $str.="<select name='cate'>";
  foreach ($rs as $key=>$val){
    $selectedstr='';
    if ($val['id'] == $selected){
      $selectedstr="selected";
    }
    $str.="<option {$selectedstr}>{$val['title']}</option>";
  }
  return $str.="</select>";
}
echo displayCate(0,3);

?>