数组 函数
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next

(PHP 4, PHP 5)

next — 将数组中的内部指针向前移动一位

说明

mixed next ( array &$array )

返回数组内部指针指向的下一个单元的值，或当没有更多单元时返回 FALSE。

next() 和 current() 的行为类似，只有一点区别，在返回值之前将内部指针向前移动一位。这意味着它返回的是下一个数组单元的值并将数组指针向前移动了一位。如果移动指针的结果是超出了数组单元的末端，则 next() 返回 FALSE。

Warning

如果数组包含空的单元，或者单元的值是 0 则本函数碰到这些单元也返回 FALSE。要正确遍历可能含有空单元或者单元值为 0 的数组，参见 each() 函数。

Example #1 next() 及相关函数的用法示例

<?php
$transport = array('foot', 'bike', 'car', 'plane');
$mode = current($transport); // $mode = 'foot';
$mode = next($transport);    // $mode = 'bike';
$mode = next($transport);    // $mode = 'car';
$mode = prev($transport);    // $mode = 'bike';
$mode = end($transport);     // $mode = 'plane';
?>

参见 current()，end()，prev() 和 reset()。

数组 函数
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PHP手册 - N: 将数组中的内部指针向前移动一位

用户评论:

double at dumpit dot de (08-Dec-2009 09:19)

PHP: 5.2.10-2ubuntu6.3 (default apt-get installation on actual, see Date, jaunty 9.10 Ubuntu Distro - G33kWoRDs)

Have a look at your array pointer if you copy an array - the pointer will be copied, too.

For example if you got this construct:
<?php
    $array = array('zero','one','two','three','four','five','six','seven');
    $array2 = $array;
    next($array);
    echo key($array);
    echo key($array2);

    // will output:
    // 1
    // 0
?>

But if you copy the array after you've setted the pointer, the pointer will be copied, too:
<?php
    $array = array('zero','one','two','three','four','five','six','seven');
    next($array);
    $array2 = $array;
    echo key($array);
    echo key($array2);
  
    // will output:
    // 1
    // 1
?>

What's more is, that foreach not resetting the pointer after walk through:
<?php

    $array = array('zero','one','two','three','four','five','six','seven');
    next($array);
    $array2 = array();
    foreach($array AS $key => $value){
        echo $key;
        $array2[$key] = $value;
    }
    echo var_dump(key($array));
    echo key($array2);

    // will output for foreach:
    // 0 1 2 3 4 5 6 7
    // and for the keys
    // NULL
    // 0
?>

The php-functions seems to reset the pointer on the given position after walk through (i don't know the internal handling - there could be used a copy of the array, too):
<?php

    $array = array('zero','one','two','three','four','five','six','seven');
    next($array);
    $array2 = array_values($array);
    echo key($array);
    echo key($array2);

    // will output:
    // 1
    // 0
?>

There are a lot Methods like array_merge($array) that will neither reset the pointer of $array nor copy the pointer to $array2. Have a look on this.
I Hope this was a little helpfull.

ThinkMedical at Gmail dot com (02-Sep-2008 11:27)

regarding references with foreach, you can use them directly. Obviating various posts which provide many lines of 'work arounds'.

$array = array(1,2,3,4,5);

foreach($array as &$value)

or use $key

foreach($array as $key => $value)
{
    $array[$key] = '...';
}

adityabhai [at] gmail com [Aditya Bhatt] (09-May-2008 01:14)

<?php
class Steps {
  
    private $all;
    private $count;
    private $curr;
  
    public function __construct () {
    
      $this->count = 0;
    
    }
  
    public function add ($step) {
    
      $this->count++;
      $this->all[$this->count] = $step;
    
    }
  
    public function setCurrent ($step) {
    
      reset($this->all);
      for ($i=1; $i<=$this->count; $i++) {
        if ($this->all[$i]==$step) break;
        next($this->all);
      }
      $this->curr = current($this->all);
    
    }
  
    public function getCurrent () {
    
      return $this->curr;
    
    }
  
    public function getNext () {
    
      self::setCurrent($this->curr);
      return next($this->all);
    
    }
   
    public function getPrev () {
    
      self::setCurrent($this->curr);
      return prev($this->all);
    
    }
      
  }
?>

Demo Example:

<?php
   $steps = new Steps();
   $steps->add('1');
   $steps->add('2');
   $steps->add('3');
   $steps->add('4');
   $steps->add('5');
   $steps->add('6');
   $steps->setCurrent('4');
   echo $steps->getCurrent()."<br />";
   echo $steps->getNext()."<br />";
   echo $steps->getPrev()."<br />";
   $steps->setCurrent('2');
   echo $steps->getCurrent()."<br />";
   echo $steps->getNext()."<br />";
   echo $steps->getPrev()."<br />";
?>

darkside at i dot ua (11-Dec-2007 11:36)

This class implements simple operations with array

<?php
class Steps {
   
    private $all;
    private $count;
    private $curr;
   
    public function __construct () {
     
      $this->count = 0;
     
    }
   
    public function add ($step) {
     
      $this->count++;
      $this->all[$this->count] = $step;
     
    }
   
    public function setCurrent ($step) {
     
      reset($this->all);
      for ($i=1; $i<=$this->count; $i++) {
        if ($this->all[$i]==$step) break;
        next($this->all);
      }
      $this->curr = current($this->all);
     
    }
   
    public function getCurrent () {
     
      return $this->curr;
     
    }
   
    public function getNext () {
     
      self::setCurrent($this->curr);
      return next($this->all);
     
    }
       
  }
?>

usage example:

<?php
   $steps = new Steps();
   $steps->add('one');
   $steps->add('two');
   $steps->add('three');
   $steps->setCurrent('one');
   echo $steps->getCurrent()."<br />";
   echo $steps->getNext()."<br />";
   $steps->setCurrent('two');
   echo $steps->getCurrent()."<br />";
   echo $steps->getNext()."<br />";
?>

gg2005 at gmail dot com (06-Feb-2007 09:32)

Don't confuse next with continue!

If you're a Perl developer starting with PHP, you might try to use "next" inside a loop to skip to the next iteration...  

i.e.,

foreach ($things as $thing) {
  if (something I don't like about $thing) {
   next;
  }
  blah....
}

The php compiler will take next... but it's not going to work.

Do this instead:
foreach ($things as $thing) {
  if (something I don't like about $thing) {
   continue;
  }
  blah....
}

GPatmore (12-Oct-2006 08:14)

If your using a foreach loop, unless you for a reference, PHP will make a copy of the array to use it the loop.

So, when I need to take a different action for the last element in the array I use the following:

<?php
$ary  = explode(',','a,b,c,d,e,f,g');
foreach($ary as $a){
    print 'letter ' . $a;
    if(next($ary)){
        print '<br>';
    }else{
        print '<br>dun!';
    }
}
?>

Output:

letter a
letter b
letter c
letter d
letter e
letter f
letter g
dun!

NOTE::
PHP5 has added an ability to reference the variable in a foreach like:

<?php
foreach($ary as &$a){}
?>

this will probably cause undesired results when using the method above.

also if the array is changed in any way as to cause the length of the original array to become different then the copy, it will not work. 
Consider the following example:

<?php
$ary  = explode(',','a,b,c,d,e,f,g');
foreach($ary as $a){
    print 'letter ' . $a;
    if(next($ary)){
        unset($ary[count($ary) - 1]);
        print '<br>';
    }else{
        print '<br>dun!';
    }
}
?>

output:

letter a
letter b
letter c
letter d
dun!letter e
dun!letter f
dun!letter g
dun!

tom at nono dot be (27-Jul-2006 12:19)

I see some questions like "how can I know if an array has a next value without changing its internal pointer" and some pretty complicated responses that DO work mind you and in some cases you'll need them...

But suppose you just need a different action within a foreach loop when reaching the final item:
(it won't be usefull in every situation, but in most it will)

$numOfItems = count($someArray);
$counter = 0;
foreach ($someArray as $key => value){
    $counter += 1;
    if ($counter <> $numOfItems){
        //here all next items exist
   } else {
        //final item
   }
}

Sigmar (30-May-2006 11:02)

And if you want to know if there are any array elements in array before given key, you can use this function:

function any_array_keys_before($keyname, &$array) {
    if (!is_array($array)) {
        return false;
    }
    if (empty($keyname)) {
        return false;
    }
    $set = false;
    $count = 0;
    foreach ($array as $key => $value) {
        if ($set === false && $key != $keyname) {
            $count ++;
        } else if ($key == $keyname) {
            $set = true;
        }
    }
    return $count > 0 ? true : false;
}

Sigmar (30-May-2006 10:52)

If you want to check, if there are some more elements in array after given key, you can use the following function:

function more_array_keys($keyname, &$array) {
    if (!is_array($array)) {
        return false;
    }
    if (empty($keyname)) {
        return false;
    }
    $set = false;
    $count = 0;
    foreach ($array as $key => $value) {
        if ($set === true) {
            $count++;
        }
        if ($key == $keyname) {
            $set = true;
        }
    }
    return $count > 0 ? true : false;
}

tino at infeon dot com (13-May-2006 04:48)

this may be handy and i didnt know where else to post it.. i need a simple function to cycle through an array i eventually made it into a class so i could have multiple cycles.. if you like it or find it usefull please email me and let me know

class Cycle
{
    var $position;
    var $dataArray;
    var $dataArrayCount;
   
    function Cycle()
    {
        $this->dataArray = func_get_args();
        $this->dataArrayCount = count($this->dataArray);
    }
   
    function Display()
    {
        $this->position = (!isset($this->position) || $this->position >= ($this->dataArrayCount - 1)) ? 0 : $this->position += 1;
        return $this->dataArray[$this->position];
    }
   
}

$bgColor = new Cycle('#000000', '#FFFFFF', '#FF0000');

echo $bgcolor->Display();
//returns #000000
echo $bgcolor->Display();
//returns #FFFFFF
echo $bgcolor->Display();
//returns #FF0000
echo $bgcolor->Display();
//returns #000000

brentimus (28-Apr-2005 06:10)

Papipo's function below is usefull in concept but does not work.

"Since you do not pass the array by reference, its pointer is only moved inside the function."

This is true, but the array you are manipulating in your has_next() function will have it's pointer set to the first element, not the same position as the original array. What you want to do is pass the array to the has_next() function via reference. While in the has_next() function, make a copy of the array to work on. Find out the current pointer position of the original array and set the pointer on the working copy of the array to the same element. Then you may test to see if the array has a "next" element.

Try the followig insetad:

<?php
function has_next(&$array)
{
    $A_work=$array;  //$A_work is a copy of $array but with its internal pointer set to the first element.
    $PTR=current($array);
    array_set_pointer($A_work, $PTR);

    if(is_array($A_work))
    {
        if(next($A_work)===false)
            return false;
        else
            return true;
    }
    else
        return false;
}

function array_set_pointer(&$array, $value)
{
    reset($array);
    while($val=current($array))
    {
        if($val==$value)
            break;

        next($array);
    }
}
?>

papipo's gmail account (13-Oct-2004 09:47)

I need to know if an array has more items, but without moving array's internail pointer. Thats is, a has_next() function:

<?php
function has_next($array) {
    if (is_array($array)) {
        if (next($array) === false) {
            return false;
        } else {
            return true;
        }
    } else {
        return false;
    }
}

$array = array('fruit', 'melon');
if (has_next($array)) {
    echo next($array);
}

// prints 'melon'
?>

Since you do not pass the array by reference, its pointer is only moved inside the function.
Hope that helps.

lukasz at karapuda dot com (18-Aug-2004 06:06)

This function will return the previous,next neighbors of an array entry within an associative array. If the specified $key points to the last or first element of the array, the first or last keys of the array will be returned consecutively. This is an improved version of the same function posted earlier.

<?php
function array_neighbor($arr, $key)
{
   $keys = array_keys($arr);
   $keyIndexes = array_flip($keys);
 
   $return = array();
   if (isset($keys[$keyIndexes[$key]-1])) {
       $return[] = $keys[$keyIndexes[$key]-1];
   }
   else {
       $return[] = $keys[sizeof($keys)-1];
   }
  
   if (isset($keys[$keyIndexes[$key]+1])) {
       $return[] = $keys[$keyIndexes[$key]+1];
   }
   else {
       $return[] = $keys[0];
   }
  
   return $return;
}
?>

court shrock (21-May-2004 12:36)

This code returns neighbors of the specified key.  The result will be empty if it doesn't have any neighbors.  My approach was to use the order of keys to determine neighbors, which is differnet from just getting the next/previous element in an array.  Feel free to point out stupidities :)

<?php

function array_neighbor($arr, $key)
{
    krsort($arr);
    $keys = array_keys($arr);
    $keyIndexes = array_flip($keys);
   
    $return = array();
    if (isset($keys[$keyIndexes[$key]-1]))
        $return[] = $keys[$keyIndexes[$key]-1];
    if (isset($keys[$keyIndexes[$key]+1]))
        $return[] = $keys[$keyIndexes[$key]+1];

    return $return;
}

?>

bm at ANTISPAM dot solidwave dot com (17-Apr-2004 05:49)

Take care when replacing code using reset()/next() with code using foreach as foreach does not update the array's internal pointer.  This means you cannot, say, use next() to skip an element in foreach loop, or use current() within a function to get a reference to the current element.  You probably have code depending on this internal pointer and replacing it will be more work than you anticipated.

See http://www.php.net/foreach