array_intersect_assoc
I have found the following helpful:
<?PHP
function array_merge_default($default, $data) {
$intersect = array_intersect_key($data, $default); //Get data for which a default exists
$diff = array_diff_key($default, $data); //Get defaults which are not present in data
return $diff + $intersect; //Arrays have different keys, return the union of the two
}
?>
It's use is like both of the functions it uses, but keeps defaults and _only_ defaults. It's designed for key arrays, and i'm not sure how it will work on numeric indexed arrays.
Example:
<?PHP
$default = array(
"one" => 1,
"two" => 2
);
$untrusted = array(
"one" => 42,
"three" => 3
);
var_dump(array_merge_default($default, $untrusted));
array(2) {
["two"]=>
int(2)
["one"]=>
int(42)
}
?>
array_intersect_key
(PHP 5 >= 5.1.0)
array_intersect_key — 使用键名比较计算数组的交集
说明
array array_intersect_key
( array $array1
, array $array2
[, array $ ...
] )
array_intersect_key() 返回一个数组，该数组包含了所有出现在 array1 中并同时出现在所有其它参数数组中的键名的值。
Example#1 array_intersect_key() 例子
<?php
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8);
var_dump(array_intersect_key($array1, $array2));
?>
上例将输出：
array(2) { ["blue"]=> int(1) ["green"]=> int(3) })
上例中可以看到只有 'blue' 和 'green' 两个键名出现在两个数组中，因此被返回。此外注意 'blue' 和 'green' 的值在两个数组中是不同的。但因为只检查键名，因此还是匹配。返回的值只是 array1 中的。
在 key => value 对中的两个键名仅在 (string) $key1 === (string) $key2 时被认为相等。换句话说，执行的是严格类型检查，因此字符串的表达必须完全一样。
参见 array_diff()，array_udiff()，array_diff_assoc()，array_diff_uassoc()，array_udiff_assoc()，array_udiff_uassoc()，array_diff_key()，array_diff_ukey()，array_intersect()，array_intersect_assoc()，array_intersect_uassoc() 和 array_intersect_ukey()。
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User Contributed Notesarray_intersect_key
CBWhiz at gmail dot com
05-Jan-2008 06:04
05-Jan-2008 06:04
Rod Byrnes
06-May-2007 12:10
06-May-2007 12:10
Here is a faster version than those shown below, with optimisation for the case when only two arrays are passed. In my tests with a 10000 item first array and a 5000 item second array (run 20 times) this function ran in 1.89 seconds compared with 2.66 for the version posted by dak. For a three array case, same as above but with the third array containing 3333 values, the timing is 3.25 for this version compared with 3.7 for dak's version.
<?php
if (!function_exists('array_intersect_key'))
{
function array_intersect_key($isec, $keys)
{
$argc = func_num_args();
if ($argc > 2)
{
for ($i = 1; !empty($isec) && $i < $argc; $i++)
{
$arr = func_get_arg($i);
foreach (array_keys($isec) as $key)
{
if (!isset($arr[$key]))
{
unset($isec[$key]);
}
}
}
return $isec;
}
else
{
$res = array();
foreach (array_keys($isec) as $key)
{
if (isset($keys[$key]))
{
$res[$key] = $isec[$key];
}
}
return $res;
}
}
}
?>
17-Jul-2006 08:31
Here it is a more obvious way to implement the function:
if (!function_exists('array_intersect_key')) {
function array_intersect_key()
{
$arrs = func_get_args();
$result = array_shift($arrs);
foreach ($arrs as $array) {
foreach ($result as $key => $v) {
if (!array_key_exists($key, $array)) {
unset($result[$key]);
}
}
}
return $result;
}
}
Anton Backer
31-Mar-2006 03:49
31-Mar-2006 03:49
Jesse: no, array_intersect_key does not accomplish the same thing as what you posted:
array_flip (array_intersect (array_flip ($a), array_flip ($b)))
because when the array is flipped, values become keys. having duplicate values is not a problem, but having duplicate keys is. array_flip resolves it by keeping only one of the duplicates and discarding the rest. by the time you start intersecting, you've already lost information.
dak
24-Jan-2006 12:31
24-Jan-2006 12:31
A more efficient (and, I think, simpler) compatibility implementation:
<?php
if (!function_exists('array_intersect_key'))
{
function array_intersect_key ($isec, $arr2)
{
$argc = func_num_args();
for ($i = 1; !empty($isec) && $i < $argc; $i++)
{
$arr = func_get_arg($i);
foreach ($isec as $k =>& $v)
if (!isset($arr[$k]))
unset($isec[$k]);
}
return $isec;
}
}
?>
Silvio Ginter
23-Sep-2005 08:17
23-Sep-2005 08:17
Based on the code posted by gaylord dot aulke at 100days.de
i wrote this one. This should implement this function in all versions equal or greater than PHP 4.0
function array_intersect_key($arr1, $arr2) {
$res = array();
foreach($arr1 as $key=>$value) {
$push = true;
for ($i = 1; $i < func_num_args(); $i++) {
$actArray = func_get_arg($i);
if (gettype($actArray) != 'array') return false;
if (!array_key_exists($key, $actArray)) $push = false;
}
if ($push) $res[$key] = $arr1[$key];
}
return $res;
}
gaylord dot aulke at 100days.de
04-Jul-2005 07:04
04-Jul-2005 07:04
I tried to use this function with PHP 5.0.4 under windows but the function does not seem to be implemented.
(Fatal error: Call to undefined function array_intersect_key())
This works as a workaround for 2 arrays at least:
function array_intersect_key($arr1, $arr2) {
$res = array();
foreach($arr1 as $key=>$value) {
if(array_key_exists($key, $arr2)) $res[$key] = $arr1[$key];
}
return $res;
}
aidan at php dot net
29-May-2005 11:51
29-May-2005 11:51
This functionality is now implemented in the PEAR package PHP_Compat.
More information about using this function without upgrading your version of PHP can be found on the below link:
http://pear.php.net/package/PHP_Compat