SPL的基本使用

SPL是Standard PHP Library（PHP标准库）的缩写。

根据官方定义，它是"a collection of interfaces and classes that are meant to solve standard problems"。但是，目前在使用中，SPL更多地被看作是一种使object（物体）模仿array（数组）行为的interfaces和classes。

这几天学习SPL，这是我写的一点小笔记，望日后再次使用时能够想起点滴，SPL核心便是Iterator，熟练使用Iterator可以让我们更加方便的去操作数据.

 

ArrayIterator迭代器示例

 1 <?php
 2 $fruits = array
 3 (
 4     "apple" => 'apple value',
 5     "orange" => 'orange value',
 6     "grape" => "grape value",
 7     "plum" => "plum value"
 8 );
 9 print_r($fruits);
10 echo "**** use fruits directly\n";
11 foreach ($fruits as $key => $value)
12 {
13     echo $key . ":" . $value . "\n";
14 }
15 //使用ArrayIterator遍历数组
16 $obj = new ArrayObject($fruits);
17 $it = $obj->getIterator();
18 
19 echo "***** use ArrayIterator in for\n";
20 foreach ($it as $key => $value)
21 {
22     echo $key . ":" . $value . "\n";
23 }
24 
25 echo "***** use ArrayIterator in while\n";
26 $it->rewind();//调用current之前要用rewind
27 while ($it->valid())
28 {
29     echo $it->key() . ":" . $it->current()."\n";
30     $it->next();
31 }
32 //跳过某些元素进行打印
33 echo "***** use seek before while\n";
34 $it->rewind();
35 if ($it->valid())
36 {
37     $it->seek(1);
38     while($it->valid())
39     {
40         echo $it->key() . ":" . $it->current()."\n";
41         $it->next();
42     }
43 }
44 
45 echo "***** use ksort\n";
46 $it->ksort();
47 foreach ($it as $key => $value)
48 {
49     echo $key . ":" . $value . "\n";
50 }
51 
52 echo "***** use asort\n";
53 $it->asort();
54 foreach ($it as $key => $value)
55 {
56     echo $key . ":" . $value . "\n";
57 }

ArrayIterator