In PHP, the recursive algorithm is one of the few data traversal methods we have. Let me introduce to you some useful things using recursion.
Look at a simple recursion example
Example 1
The code is as follows
| 代码如下 |
复制代码 |
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function demo($a) {
static $sum=1;
if($a > 1){
$sum*=$a;
demo(--$a);
}else{
$a=$sum;
}
return $sum;
}
echo demo(10);
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Copy code
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function demo($a) {
| 代码如下 |
复制代码 |
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class listdir{
var $depth;
var $dirname;
var $list;
var $tostring;
function listdir($dir){
$this->dirname=$dir;
$this->depth=0;
$this->tostring=”";
}
//把结果保存进多维数组
function getlist($dir=”"){
if($dir==”")$dir=$this->dirname;
$d=@dir($dir);
while(false!==($item=$d->read()))
{
if($item!=”.”&&$item!=”..”)
{
$path=$dir.”/”.$item;
if(is_dir($path)){
$this->depth+=1;
$this->getlist($path);
}else{
$this->list[$this->depth][]=$item;
}
}
}
$this->list[$this->depth]['directory']=$dir;
$this->depth-=1;
$d->close();
return $this->list;
}
//字符窜化结果
function tostring($dir=”"){
if($dir==”")$dir=$this->dirname;
$d=@dir($dir);
$this->tostring.=” n”;
$this->tostring.=”Directory:”.$dir.”n”;
while(false!==($item=$d->read()))
{
if($item!=”.”&&$item!=”..”)
{
$path=$dir.”/”.$item;
if(is_dir($path)){
$this->depth+=1;
$this->tostring($path);
}else{
$this->tostring.=”- ”.$item.”
n”;
}
}
}
$this->depth-=1;
$d->close();
$this->tostring.=” n”;
return $this->tostring;
}
}
$wapdir=”jquery”;
$d=new listdir($wapdir);
echo $d->tostring();
?>
输出结果：
Directory:jquery
- jquery-1.3.2.js
- jquery-1.3.2.min.js
- jquery-1.3.2-vsdoc2.js
- test.html
- common.js
Directory:jquery/d
- common.js
- jquery-1.3.2.js
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static $sum=1; |
if($a > 1){
$sum*=$a;
demo(--$a);
}else{
$a=$sum;
}
return $sum;
}
echo demo(10);
Example 2
Traverse directories
| The code is as follows
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Copy code
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class listdir{
var $depth;
var $dirname;
var $list;
var $tostring;<🎜>
<🎜>function listdir($dir){
$this->dirname=$dir;
$this->depth=0;
$this->tostring=””;
}
//Save the result into a multi-dimensional array
function getlist($dir=""){
if($dir==”")$dir=$this->dirname;
$d=@dir($dir);
while(false!==($item=$d->read()))
{
if($item!=”.”&&$item!=”..”)
{
$path=$dir.”/”.$item;
if(is_dir($path)){
$this->depth+=1;
$this->getlist($path);
}else{
$this->list[$this->depth][]=$item;
}
}
}
$this->list[$this->depth]['directory']=$dir;
$this->depth-=1;
$d->close();
return $this->list;
}
//Character channeling result
function tostring($dir=""){
if($dir==”")$dir=$this->dirname;
$d=@dir($dir);
$this->tostring.=”n”;
$this->tostring.=”Directory:”.$dir.”n”;
while(false!==($item=$d->read()))
{
if($item!=”.”&&$item!=”..”)
{
$path=$dir.”/”.$item;
if(is_dir($path)){
$this->depth+=1;
$this->tostring($path);
}else{
$this->tostring.=”- ”.$item.”
n”;
}
}
}
$this->depth-=1;
$d->close();
$this->tostring.=” n”;
return $this->tostring;
}
}
$wapdir=”jquery”;
$d=new listdir($wapdir);
echo $d->tostring();
?>
Output result:
Directory:jquery
- jquery-1.3.2.js
- jquery-1.3.2.min.js
- jquery-1.3.2-vsdoc2.js
- test.html
- common.js
Directory:jquery/d
- common.js
- jquery-1.3.2.js
http://www.bkjia.com/PHPjc/632807.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632807.htmlTechArticleIn php, the recursive algorithm is a data traversal method that we can’t compare with. Let me tell you about it below. Let’s introduce some useful things using recursion. Look at a simple recursion example...
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