php变量的引用传值详细教程

function test(&$a)
{
$a=$a+100;
}
$b=1;
echo $b;//输出１
test($b); //这里$b传递给函数的其实是$b的变量内容所处的内存地址，通过在函数里改变$a的值　就可以改变$b的值了
echo "<br>";
echo $b;//输出101

function &test()
{
static $b=0;//申明一个静态变量
$b=$b+1;
echo $b;
return $b;
}

$a=test();//这条语句会输出　$b的值　为１
$a=5;
$a=test();//这条语句会输出　$b的值　为2

$a=&test();//这条语句会输出　$b的值　为3
$a=5;
$a=test();//这条语句会输出　$b的值　为6

<?
class a{
var $abc="ABC";
}
$b=new a;
$c=$b;
echo $b->abc;//这里输出ABC
echo $c->abc;//这里输出ABC
$b->abc="DEF";
echo $c->abc;//这里输出DEF
?>

<?php
$a = 1;
$b =& $a;
unset ($a);
?>

function getCatTopId($cat_id)
{
    if ($cat_id)
    {
        $res = Array();
        $sql = 'SELECT cat_id, parent_id'
             . ' FROM ' . $GLOBALS['ecs']->table('category')
             . ' WHERE cat_id = ' . $cat_id . ' AND is_show = 1';

        $res = $GLOBALS['db']->getAll($sql);

        if ($res[0]['parent_id'] > 0)
        {
            getCatTopId($res[0]['parent_id']);
        }
        else
        {
            return $res[0]['cat_id'];
        }
    }
    else
    {
        return 1;
    }
}

function getCatTopId($cat_id)
{
    if ($cat_id)
    {
        $res = Array();

        $sql = 'SELECT cat_id, parent_id'
             . ' FROM ' . $GLOBALS['ecs']->table('category')
             . ' WHERE cat_id = ' . $cat_id . ' AND is_show = 1';

        $res = $GLOBALS['db']->getAll($sql);

        if ($res[0]['parent_id'] > 0)
        {
            return getCatTopId($res[0]['parent_id']); // 修改处，多写个 return ，让函数返回值
        }
        else
        {
            return $res[0]['cat_id'];
        }    }
    else
    {
        return 1;
    }
}

<?php
/**
* 通用的树型类，可以生成任何树型结构
*/
class tree
{
 /**
 * 生成树型结构所需要的2维数组
 * @var array
 */
 var $arr = array();

 /**
 * 生成树型结构所需修饰符号，可以换成图片
 * @var array
 */
 var $icon = array('│','├','└');

 /**
 * @access private
 */
 var $ret = '';

 /**
 * 构造函数，初始化类
 * @param array 2维数组，例如：
 * array(
 *      1 => array('id'=>'1','parentid'=>0,'name'=>'一级栏目一'),
 *      2 => array('id'=>'2','parentid'=>0,'name'=>'一级栏目二'),
 *      3 => array('id'=>'3','parentid'=>1,'name'=>'二级栏目一'),
 *      4 => array('id'=>'4','parentid'=>1,'name'=>'二级栏目二'),
 *      5 => array('id'=>'5','parentid'=>2,'name'=>'二级栏目三'),
 *      6 => array('id'=>'6','parentid'=>3,'name'=>'三级栏目一'),
 *      7 => array('id'=>'7','parentid'=>3,'name'=>'三级栏目二')
 *      )
 */
 function tree($arr=array())
 {
       $this->arr = $arr;
    $this->ret = '';
    return is_array($arr);
 }

    /**
 * 得到父级数组
 * @param int
 * @return array
 */
 function get_parent($myid)
 {
  $newarr = array();
  if(!isset($this->arr[$myid])) return false;
  $pid = $this->arr[$myid]['parentid'];
  $pid = $this->arr[$pid]['parentid'];
  if(is_array($this->arr))
  {
   foreach($this->arr as $id => $a)
   {
    if($a['parentid'] == $pid) $newarr[$id] = $a;
   }
  }
  return $newarr;
 }

    /**
 * 得到子级数组
 * @param int
 * @return array
 */
 function get_child($myid)
 {
  $a = $newarr = array();
  if(is_array($this->arr))
  {
   foreach($this->arr as $id => $a)
   {
    if($a['parentid'] == $myid) $newarr[$id] = $a;
   }
  }
  return $newarr ? $newarr : false;
 }

    /**
 * 得到当前位置数组
 * @param int
 * @return array
 */
 function get_pos($myid,&$newarr)
 {
  $a = array();
  if(!isset($this->arr[$myid])) return false;
        $newarr[] = $this->arr[$myid];
  $pid = $this->arr[$myid]['parentid'];
  if(isset($this->arr[$pid]))
  {
      $this->get_pos($pid,$newarr);
  }
  if(is_array($newarr))
  {
   krsort($newarr);
   foreach($newarr as $v)
   {
    $a[$v['id']] = $v;
   }
  }
  return $a;
 }

 /**
  * -------------------------------------
  *  得到树型结构
  * -------------------------------------
  * @author  Midnight(杨云洲),  yangyunzhou@foxmail.com
  * @param $myid 表示获得这个ID下的所有子级
  * @param $str 生成树形结构基本代码, 例如: "<option value=$id $select>$spacer$name</option>"
  * @param $sid 被选中的ID, 比如在做树形下拉框的时候需要用到
  * @param $adds
  * @param $str_group
  * @return unknown_type
  */
 function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '')
 {
  $number=1;
  $child = $this->get_child($myid);
  if(is_array($child))
  {
      $total = sqlserver/42852.htm target=_blank >count($child);
   foreach($child as $id=>$a)
   {
    $j=$k='';
    if($number==$total)
    {
     $j .= $this->icon[2];
    }
    else
    {
     $j .= $this->icon[1];
     $k = $adds ? $this->icon[0] : '';
    }
    $spacer = $adds ? $adds.$j : '';
    $selected = $id==$sid ? 'selected' : '';
    @extract($a);
    $parentid == 0 && $str_group ? eval("$nstr = "$str_group";") : eval("$nstr = "$str";");
    $this->ret .= $nstr;
    $this->get_tree($id, $str, $sid, $adds.$k.'&nbsp;',$str_group);
    $number++;
   }
  }
  return $this->ret;
 }
    /**
 * 同上一方法类似,但允许多选
 */
 function get_tree_multi($myid, $str, $sid = 0, $adds = '')
 {
  $number=1;
  $child = $this->get_child($myid);
  if(is_array($child))
  {
      $total = count($child);
   foreach($child as $id=>$a)
   {
    $j=$k='';
    if($number==$total)
    {
     $j .= $this->icon[2];
    }
    else
    {
     $j .= $this->icon[1];
     $k = $adds ? $this->icon[0] : '';
    }
    $spacer = $adds ? $adds.$j : '';

    $selected = $this->have($sid,$id) ? 'selected' : '';
    //echo $sid.'=>'.$id.' : '.$selected.' . <br/>';
    @extract($a);
    eval("$nstr = "$str";");
    $this->ret .= $nstr;
    $this->get_tree_multi($id, $str, $sid, $adds.$k.'&nbsp;');
    $number++;
   }
  }
  return $this->ret;
 }

 function have($list,$item){
  return(strpos(',,'.$list.',',','.$item.','));
 }
}
?>

function selectSort($arr,$style)
             {
                 $temp=0;
                 for($i=0;$i<count($arr)-1;$i++)
                 {
                     for($j=$i+1;$j<count($arr);$j++)
                     {
                         if($style=='bts') $op=$arr[$i]<$arr[$j];
                         else if($style=='stb') $op=$arr[$i]>$arr[$j];
                         if($op)
                         {
                             $temp=$arr[$i];
                             $arr[$i]=$arr[$j];
                             $arr[$j]=$temp;
                         }
                     }
                 }
                 foreach ($arr as $key => $value)
                 {
                     echo $value.',';   
                 }
             }
             $arr1=array(21.5,33,90,7,-4,5,55,11);
             selectSort($arr1,'stb');

function maoPao($arr,$style)    {
                 $temp=0;
                 for($i=0;$i<count($arr)-1;$i++)
                 {
                     for($j=0;$j<count($arr)-1-$i;$j++)
                     {
                         if($style=='bts') $op=$arr[$j]<$arr[$j+1];
                         else if($style=='stb') $op=$arr[$j]>$arr[$j+1];
                         if($op)
                         {
                             $temp=$arr[$j];
                             $arr[$j]=$arr[$j+1];
                             $arr[$j+1]=$temp;
                         }
                     }
                 }
                 foreach ($arr as $key => $value)
                 {
                     echo $value.',';   
                 }
             }
             $arr1=array(101,101,-9,-8,0,76,1,57,43,90,23,-56);
             maoPao($arr1,'stb');//small to big

function insertSort($arr,$style)
             {
                 $temp=0;
                 for($i=1;$i<count($arr);$i++)
                 {
                     for($j=0;$j<$i;$j++)
                     {
                         if($style=='bts') $op=$arr[$j]<$arr[$i];
                         else if($style=='stb') $op=$arr[$j]>$arr[$i];
                         if($op)
                         {
                             $temp=$arr[$j];
                             $arr[$j]=$arr[$i];
                             $arr[$i]=$temp;
                         }
                     }
                 }
                 foreach ($arr as $key => $value)
                 {
                     echo $value.',';   
                 }
             }
             $arr1=array(4,7,0,-7,1,14,5);
             insertSort($arr1,'bts');