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PHP : Function Reference : Array Functions : next

next

Advance the internal array pointer of an array (PHP 4, PHP 5, PECL axis2:0.1.0-0.1.1 xmlreader:1.0-1.0.1)
mixed next ( array &array )

Returns the array value in the next place that's pointed to by the internal array pointer, or FALSE if there are no more elements.

next() behaves like current(), with one difference. It advances the internal array pointer one place forward before returning the element value. That means it returns the next array value and advances the internal array pointer by one. If advancing the internal array pointer results in going beyond the end of the element list, next() returns FALSE.

Warning:

This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE, such as 0 or "". Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

Note:

You won't be able to distinguish the end of an array from a boolean FALSE element. To properly traverse an array which may contain FALSE elements, see the each() function.

Example317.Example use of next() and friends

<?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';
?>


See also current(), end(), prev(), reset(), and each().

Related Examples ( Source code ) » next















Code Examples / Notes » next

tino

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


lukasz

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

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

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


brentimus

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);
   }
}
?>


gpatmore

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 '
';
}else{
print '
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 '
';
}else{
print '
dun!';
}
}
?>
output:
letter a
letter b
letter c
letter d
dun!letter e
dun!letter f
dun!letter g
dun!


sigmar

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;
}


tom

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
  }
}


papipo's gmail account

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.


gg2005

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....
}


sigmar

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;
}


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