ID: 47330
User updated by: thuejk at gmail dot com
Reported By: thuejk at gmail dot com
Status: Open
Bug Type: Documentation problem
Operating System: All
PHP Version: Irrelevant
New Comment:
Ah, I misunderstood.
Null is not a possible array index, hence my confusion. Array indices
are always strings or ints. (as I found out when debugging a face of a
float being silently truncated to int when used as an array index...)
Previous Comments:
------------------------------------------------------------------------
[2009-08-26 16:20:34] torben@php.net
You're correct that key() does not return NULL if the array value is
NULL, but that's not what I said; I said "array index", not "array
value".
That said, I must apologize as I was also incorrect: key() does not in
fact return NULL if the array index is NULL; it returns the empty
string. That's what I get for posting when I should have gone to bed
instead.
Re-opening.
------------------------------------------------------------------------
[2009-08-26 08:58:00] thuejk at gmail dot com
>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.
------------------------------------------------------------------------
[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";
}
------------------------------------------------------------------------
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
http://bugs.php.net/47330
--
Edit this bug report at http://bugs.php.net/?id=47330&edit=1