I'm trying to find the difference in 2 arrays.
$inven_old = array(1,2,3,4);
$inven_new = array(1,2,3,4,5);
$result = array_diff($inven_old, $inven_new);
print_r($result);
Why is the outcome nothing?
Shouldn't it be "5" ?
If not, how can I do what I'm trying to do?
Returns an array containing all the entries from array1 that are not present in any of the other arrays.
http://php.net/manual/en/function.array-diff.php
array_diff() gives the result of subtracting all arrays except the first, from the first. Thus, things which are in the second array but not the first won't show up. (In other words, it's not the symmetric difference.)
http://www.php.net/manual/en/function.array-diff.php
Returns an array containing all the entries from array1 that are not present in any of the other arrays.
So if you do:
$result = array_diff($inven_new, $inven_old);
The result will contain "5".
Bonus: If you need something that works regardless of the order of the arrays, try:
$result = array_diff($a + $b, array_intersect($a, $b));
A very late response but maybe this will help someone sometime ..
function array_deep_diff($d1, $d2) {
if (is_array($d1) && is_array($d2)) {
$diff = array();
foreach (array_unique(array_merge(array_keys($d1), array_keys($d2))) as $key) {
if (!array_key_exists($key, $d1)) {
$diff['added'][$key] = $d2[$key];
} else if (!array_key_exists($key, $d2)) {
$diff['removed'][$key] = $d1[$key];
} else {
$tmp = array_deep_diff($d1[$key], $d2[$key]);
if (!empty($tmp)) $diff[$key] = $tmp;
}
}
return $diff;
} else if (!is_array($d1) && !is_array($d2)) {
if ($d1 == $d2) return array();
$ret = "$d1 ---> $d2";
// just a little touch for numerics, might not be needed
if (is_numeric($d1) && is_numeric($d2)) {
if ($d1 > $d2) $ret .= ' [- ' . ($d1 - $d2) . ']';
if ($d1 < $d2) $ret .= ' [+ ' . ($d2 - $d1) . ']';
}
return $ret;
} else {
return array('Array compared with NonArray');
}
}
to make it work as you expect you need to reverse arguments:
$result = array_diff($inven_new, $inven_old);
Otherwise you are checking which elements are missing in the inven_new, and obsiously none is missing.
The second array should come first
$inven_old = array(1,2,3,4);
$inven_new = array(1,2,3,4,5);
$result = array_diff($inven_new, $inven_old);
print_r($result);
There is no built-in function but you can easily write a custom one (http://ideone.com/UNRKV):
$old = array(5,5,4);
$new = array(5,5,4,4);
function array_subtract($a, $b)
{
foreach ($b as $val) {
$i = array_search($val, $a);
if ($i !== false) {
unset($a[$i]);
}
}
return array_values($a);
}
$result = array_subtract($new, $old);
var_dump($result);
This consumes from the first array ($old) until all are gone:
$result = array();
$old = array_count_values($old);
foreach($new as $value)
{
@$old[$value] ? $old[$value]-- : $result[] = $value;
}
Result:
$old = array(5,5,4);
$new = array(5,5,4,4);
...
array(1) {
[0]=>
int(4)
}
var_dump($result)to see it's structureReturns an array containing all the entries from array1 that are not present in any of the other arrays.