#47330 [Bgs]: key return value should be specified
| From: | thuejk at gmail dot com | Date: | Wed, 26 Aug 2009 08:58:00 +0000 |
| Subject: | #47330 [Bgs]: key return value should be specified | ||
| References: | 1 | Groups: | php.doc.bugs |
| Request: | Send a blank email to doc-bugs+get-2665@lists.php.net to get a copy of this message | ||
ID: 47330
User updated by: thuejk at gmail dot com
Reported By: thuejk at gmail dot com
Status: Bogus
Bug Type: Documentation problem
Operating System: All
PHP Version: Irrelevant
New Comment:
>key() also returns NULL if the array index currently being examined
>contains NULL, and therefore gives no useful information as to
whether
>the end of the array has been passed or not.
And anyway, if theis is a case it is an even worse bug than my original
report, since the manual states
Return Values: Returns the index.
It specifically does NOT say anything about returning null if the array
value is null.
Previous Comments:
------------------------------------------------------------------------
[2009-08-26 08:38:10] thuejk at gmail dot com
Umm, sorry, typo, the code
<?php
$array = Array(0 => null);
reset($array);
var_dump(current($array));
var_dump(key($array));
?>
of course prints out
int(null)
int(0)
------------------------------------------------------------------------
[2009-08-26 08:35:51] thuejk at gmail dot com
Nope, not true. The code
<?php
$array = Array(0 => null);
reset($array);
var_dump(current($array));
var_dump(key($array));
?>
Prints out
int(1)
int(0)
But yes,
<?php
if (each($array) === false) {
$beyond = true;
} else {
$beyond = false;
prev($array);
}
?>
is the same as
<?php
$beyond = key($array) === null;
?>
Just not as handy.
I know about the
foreach ($arr as $key => $val) {
echo "Got $key => $val\n";
}
syntax, but sometimes you need the array iterators, like the following
function:
<?php
//A mergesort which preserves keys.
//The naming is like the "a" in build-in function asort()
public static function amergesort(Array &$array,
$cmp_function='strcmp') {
// Arrays of size < 2 require no action.
if (count($array) < 2) return;
// Split the array in half
$halfway = count($array) / 2;
$array1 = array_slice($array, 0, $halfway, true);
$array2 = array_slice($array, $halfway, sizeof($array), true);
// Recurse to sort the two halves
self::amergesort($array1, $cmp_function);
self::amergesort($array2, $cmp_function);
// If all of $array1 is <= all of $array2, just append them.
$value1 = end($array1);
$key1 = key($array);
reset($array1);
$value2 = reset($array2);
$keys2 = key($array2);
if (call_user_func($cmp_function, $value1, $value2) < 1) {
$array = $array1;
//mergesort will renumber numeric keys
foreach ($array2 as $key2 => $value2) {
$array[$key2] = $value2;
}
return;
}
// Merge the two sorted arrays into a single sorted array
$array = array();
while (true) {
$value1 = current($array1);
$key1 = key($array1);
$value2 = current($array2);
$key2 = key($array2);
if ($key1 === null) {
//$array1 is empty - append array 2
do {
$array[$key2] = $value2;
$value2 = next($array2);
$key2 = key($array2);
} while ($key2 !== null);
break;
} else if ($key2 === null) {
//$array2 is empty - append array 1
do {
$array[$key1] = $value1;
$value1 = next($array1);
$key1 = key($array1);
} while ($key1 !== null);
break;
} else {
//compare elements from $array1, $array2 to see which to
append
if (call_user_func($cmp_function, $value1, $value2) < 1) {
$array[$key1] = $value1;
next($array1);
} else {
$array[$key2] = $value2;
next($array2);
}
}
}
return;
}
?>
------------------------------------------------------------------------
[2009-08-26 07:24:43] torben@php.net
key() also returns NULL if the array index currently being examined
contains NULL, and therefore gives no useful information as to whether
the end of the array has been passed or not.
To successfully traverse the array, key() is not the appropriate
method. Either of the following will server you better:
foreach ($arr as $key => $val) {
echo "Got $key => $val\n";
}
or
reset($arr);
while (list($key, $val) = each($arr)) {
echo "$key => $val\n";
}
------------------------------------------------------------------------
[2009-02-06 16:47:19] thuejk at gmail dot com
Description:
------------
Currently there is no documented way to check whether an array iterator
is pointing beyond the end of the array.
It would be nice if key($array) could be counted on to return null if
that was the case.
key does return null in practice, however the documentation does not
specify the fact, making me fear that the behaviour could change in the
future.
See also http://dk.php.net/manual/en/function.key.php
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=47330&edit=1