pos
Here's a slight revision to xmlich02's backwards iteration example. The problem with his/her example is that it will halt if any of the array elements are boolean false, while this version will not.
<?php
end($ar);
while ( !is_null($key = key($ar)) ) {
$val = current($ar);
echo "{$key} => {$val}\n";
prev($ar);
}
?>
prev
(PHP 4, PHP 5)
prev — Rewind the internal array pointer
Description
Rewind the internal array pointer.
prev() behaves just like next(), except it rewinds the internal array pointer one place instead of advancing it.
Parameters
-
array -
The input array.
Return Values
Returns the array value in the previous place that's pointed to by
the internal array pointer, or FALSE if there are no more
elements.
Examples
Example #1 Example use of prev() 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';
?>
Notes
Warning
This function may
return Boolean FALSE, but may also return a non-Boolean value which
evaluates to FALSE. 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 beginning of an array from a boolean
FALSEelement. To properly traverse an array which may containFALSEelements, see the each() function.
See Also
- current() - Return the current element in an array
- end() - Set the internal pointer of an array to its last element
- next() - Advance the internal array pointer of an array
- reset() - Set the internal pointer of an array to its first element
- each() - Return the current key and value pair from an array and advance the array cursor
add a note
User Contributed Notes
prev - [2 notes]
soapergem at gmail dot com ¶
3 years ago
xmlich02 at stud dot fit dot vutbr dot cz ¶
5 years ago
// example of backward iteration
$ar = array ( 'a', 'b', 'c', 'd', 'e', 'f') ;
print_r($ar);
end($ar);
while($val = current($ar)) {
echo $val.' ';
prev($ar);
}