在循环里如何使用<optgroup>标签

$data = array (
  0 => 
  array (
    'id' => '1',
    'name' => 'WEB编程',
    'parentid' => '0',
  ),
  1 => 
  array (
    'id' => '2',
    'name' => 'PHP',
    'parentid' => '1',
  ),
  2 => 
  array (
    'id' => '3',
    'name' => 'Ajax',
    'parentid' => '1',
  ),
  3 => 
  array (
    'id' => '4',
    'name' => 'java',
    'parentid' => '1',
  ),
  4 => 
  array (
    'id' => '5',
    'name' => 'WinForm编程',
    'parentid' => '0',
  ),
  5 => 
  array (
    'id' => '6',
    'name' => 'VB',
    'parentid' => '5',
  ),
  6 => 
  array (
    'id' => '7',
    'name' => 'VC',
    'parentid' => '5',
  ),
);

这么一个数组，想得到下面的效果。

<select name="categorys">
    <optgroup label="WEB编程">
        <option value="2" >PHP</option>
        <option value="3" >Ajax</option>
        <option value="4" >java</option>
    </optgroup>
 
    <optgroup label="WinForm编程">
        <option value="6" >VB</option>
        <option value="7" >VC</option>
    </optgroup>
</select>

难点在于如何在foreach里判断把<option>包含在<optgroup>里，折腾了半天也没出办法。请高手指点如何完成。

$data = array (
  0 =>  array (
    'id' => '1',
    'name' => 'WEB编程',
    'parentid' => '0',
  ),
  1 => array (
    'id' => '2',
    'name' => 'PHP',
    'parentid' => '1',
  ),
  2 => array (
    'id' => '3',
    'name' => 'Ajax',
    'parentid' => '1',
  ),
  3 => array (
    'id' => '4',
    'name' => 'java',
    'parentid' => '1',
  ),
  4 => array (
    'id' => '5',
    'name' => 'WinForm编程',
    'parentid' => '0',
  ),
  5 => array (
    'id' => '6',
    'name' => 'VB',
    'parentid' => '5',
  ),
  6 => array (
    'id' => '7',
    'name' => 'VC',
    'parentid' => '5',
  ),
);
 
echo '<select name="categorys">';
foreach($data as $v) {
  if($v['parentid'] == 0)
    echo "<optgroup label='$v[name]'>";
  else
    echo "<option value='$v[id]' >$v[name]</option>";
}
echo '</select>';

唠叨大哥，你上面的操作还是缺了结束符啊</optgroup>

我就是在苦闷如何把这个</optgroup>加进去。

echo "<optgroup label='$v[name]'>$v[name]</optgroup>";

稍微改下就行了。

$data = array (
  0 => 
  array (
    'id' => '1',
    'name' => 'WEB编程',
    'parentid' => '0',
  ),
  1 => 
  array (
    'id' => '2',
    'name' => 'PHP',
    'parentid' => '1',
  ),
  2 => 
  array (
    'id' => '3',
    'name' => 'Ajax',
    'parentid' => '1',
  ),
  3 => 
  array (
    'id' => '4',
    'name' => 'java',
    'parentid' => '1',
  ),
  4 => 
  array (
    'id' => '5',
    'name' => 'WinForm编程',
    'parentid' => '0',
  ),
  5 => 
  array (
    'id' => '6',
    'name' => 'VB',
    'parentid' => '5',
  ),
  6 => 
  array (
    'id' => '7',
    'name' => 'VC',
    'parentid' => '5',
  ),
);
$tempArray = array();
foreach($data as $item){
    $tempArray[$item['parentid']][$item['id']] = $item['name'];
}
echo '<select name="categorys">';
foreach($tempArray[0] as $parentid=>$name){
    echo "<optgroup label=\"$name\">";
    foreach($tempArray[$parentid] as $id=>$name){
        echo "<option value=\"$id\" >$name</option>";
    }
    echo '</optgroup>';
}
echo '</select>';

只是foreach了三次怕效率较差，不知还没有有别的方法。

重做数组的话……

$data = array (
  array (
    'id' => '1',
    'name' => 'WEB编程',
    'parentid' => '0',
    'sub'=>
     array(
          array(
            'id' => '2',
            'name' => 'PHP',
            'parentid' => '1',
          ),
          array (
            'id' => '3',
            'name' => 'Ajax',
            'parentid' => '1',
          ),
          array (
            'id' => '4',
            'name' => 'java',
            'parentid' => '1',
          )
    )
  ),
  array (
    'id' => '5',
    'name' => 'WinForm编程',
    'parentid' => '0',
    'sub'=>
    array(
          array (
            'id' => '6',
            'name' => 'VB',
            'parentid' => '5',
          ),
          array (
            'id' => '7',
            'name' => 'VC',
            'parentid' => '5',
          )
    )
  )
);
echo '<select style="width:200px;">';
for($i=0,$il=count($data);$i<$il;$i++){
    echo '<optgroup label="'.$data[$i]['name'].'">';
    for($j=0,$jl=count($data[$i]['sub']);$j<$jl;$j++){
        echo '<option>'.$data[$i]['sub'][$j]['name'].'</option>';
    }
    echo '<optgroup>';
}
echo '</select>';

是吗？
哦，是少了个 </optgroup>
不过我测试代码时并没有感觉出有与没有的差异

一定要有的话，就加个开关变量。要多次循环干什么？

echo '<select name="categorys">';
$k = false;
foreach($data as $v) {
  if($v['parentid'] == 0) {
    echo "<optgroup label='$v[name]'>";
    $k = true;
  }else {
    if($k) echo '</optgroup>';
    echo "<option value='$v[id]' >$v[name]</option>";
    $k = false;
  }
}
echo '</select>';

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