我知道这是一个简单的，但我就是不知道顺序错在哪里。
<?php
class StringIterator implements \Iterator
{
private $_string;
private $_length;
private $_position;
public function __construct($string)
{
if(empty($string))
{
throw new \InvalidArgumentException(sprintf('The specified string is empty'));
}//end if
$this->_string = $string;
$this->_length = strlen($this->_string);
$this->rewind(); //setting the initial position instead of having it all over the place.
}//end func
public function current()
{
return $this->_string[$this->_position];
}//end func
public function key()
{
return $this->_position;
}//end func
public function rewind()
{
$this-> _position = -1;
}//end func
public function next()
{
$this-> _position++;
}//end func
public function valid()
{ //why is it that your doing this instead of...
/*
* return isset(this->_string[this->_position]);
*
*
*/
return $this->_position < $this->_length;
}//end func
}//结束类
TEST CLASS
<?php
require_once __DIR__. '/../src/Iterators/StringIterator.php';
class StringIteratorTest extends PHPUnit_Framework_TestCase
{
//each method must begin with TEST
public function testInitializing()
{
$iterator = new \Iterators\StringIterator("Hello World");
$this->assertEquals(true,$iterator->valid());
}//end func
/**
* @expectedException InvalidArgumentException
*/
public function testInitException()
{
$iterator = new \Iterators\StringIterator("");
}//end func
public function testTraverse()
{
$string ="Hello World";
$iterator = new \Iterators\StringIterator($string);
$count =0;
$iterator->rewind();
//test to make sure the next() runs.
//The iterator interface defines the method Key key()= $key
//Iterator::current() = $char (gets the current value at the position)
foreach($iterator as $key=>$char)
{
$this->assertEquals($count,$key);
$this->assertEquals($string[$count],$char);
++$count;
$this->next();
}//end 4e
}//end func
//tests that the internal pointer (it) is at a valid position in that container that is being iterated
public function testValid()
{
$iterator = new \Iterators\StringIterator($string);
}//end func
//tests the rewind method back to the start of the container.
public function testRewind()
{
$string="Bye";
$iterator = new \Iterators\StringIterator($string);
for( $i = 0; $i< strlen($string) + 1; ++$i){
$iterator->next();
}//end for
$this->assertEquals(false,$iterator->valid());
$iterator->rewind();
$this->assertEquals(true,$iterator->valid());
}
}
有问题的问题：当我运行测试（phpunit test）时，它说明实际测试组件current() (return line)的循环和循环中存在错误foreach
foreach($iterator as $key=>$char)
{
$this->assertEquals($count,$key);
$this->assertEquals($string[$count],$char);
++$count;
$this->next();
}//end 4e
根据我的研究，我知道这与我在foreach循环中调用 next 的顺序有关，我可以准确地弄清楚它需要什么......