Yep, thinking about it replacing from back to front, this works a trick!
here's a quick repalcement for PHP <=5.3
<?php
if (!function_exists('array_replace')){ function array_replace(){
$array=array();
$n=func_num_args();
while ($n-- >0) {
$array+=func_get_arg($n);
}
return $array;
}}
?>
array_replace
(PHP 5 >= 5.3.0)
array_replace — Replaces elements from passed arrays into the first array
Description
&$array
, array &$array1
[, array &$...
] )
array_replace() replaces the values of the first
array
with the same values from all the following
arrays. If a key from the first array exists in the second array, its value
will be replaced by the value from the second array. If the key exists in the
second array, and not the first, it will be created in the first array.
If a key only exists in the first array, it will be left as is.
If several arrays are passed for replacement, they will be processed
in order, the later arrays overwriting the previous values.
array_replace() is not recursive : it will replace values in the first array by whatever type is in the second array.
Parameters
-
array
-
The array in which elements are replaced.
-
array1
-
The array from which elements will be extracted.
-
...
-
More arrays from which elements will be extracted. Values from later arrays overwrite the previous values.
Return Values
Returns an array, or NULL
if an error occurs.
Examples
Example #1 array_replace() example
<?php
$base = array("orange", "banana", "apple", "raspberry");
$replacements = array(0 => "pineapple", 4 => "cherry");
$replacements2 = array(0 => "grape");
$basket = array_replace($base, $replacements, $replacements2);
print_r($basket);
?>
The above example will output:
Array ( [0] => grape [1] => banana [2] => apple [3] => raspberry [4] => cherry )
See Also
- array_replace_recursive() - Replaces elements from passed arrays into the first array recursively

Instead of calling this function, it's often faster and simpler to do this instead:
<?php
$array_replaced = $array2 + $array1;
?>
If you need references to stay intact:
<?php
$array2 += $array1;
?>
I got hit with a noob mistake. :)
When the function was called more than once, it threw a function redeclare error of course. The enviroment I was coding in never called it more than once but I caught it in testing and here is the fully working revision. A simple logical step was all that was needed.
With PHP 5.3 still unstable for Debian Lenny at this time and not knowing if array_replace would work with multi-dimensional arrays, I wrote my own. Since this site has helped me so much, I felt the need to return the favor. :)
<?php
// Polecat's Multi-dimensional array_replace function
// Will take all data in second array and apply to first array leaving any non-corresponding values untouched and intact
function polecat_array_replace( array &$array1, array &$array2 ) {
// This sub function is the iterator that will loop back on itself ad infinitum till it runs out of array dimensions
if(!function_exists('tier_parse')){
function tier_parse(array &$t_array1, array&$t_array2) {
foreach ($t_array2 as $k2 => $v2) {
if (is_array($t_array2[$k2])) {
tier_parse($t_array1[$k2], $t_array2[$k2]);
} else {
$t_array1[$k2] = $t_array2[$k2];
}
}
return $t_array1;
}
}
foreach ($array2 as $key => $val) {
if (is_array($array2[$key])) {
tier_parse($array1[$key], $array2[$key]);
} else {
$array1[$key] = $array2[$key];
}
}
return $array1;
}
?>
[I would also like to note] that if you want to add a single dimensional array to a multi, all you must do is pass the matching internal array key from the multi as the initial argument as such:
<?php
$array1 = array( "berries" => array( "strawberry" => array( "color" => "red", "food" => "desserts"), "dewberry" = array( "color" => "dark violet", "food" => "pies"), );
$array2 = array( "food" => "wine");
$array1["berries"]["dewberry"] = polecat_array_replace($array1["berries"]["dewberry"], $array2);
?>
This is will replace the value for "food" for "dewberry" with "wine".
The function will also do the reverse and add a multi to a single dimensional array or even a 2 tier array to a 5 tier as long as the heirarchy tree is identical.
I hope this helps atleast one person for all that I've gained from this site.
I would like to add to my previous note about my polecat_array_replace function that if you want to add a single dimensional array to a multi, all you must do is pass the matching internal array key from the multi as the initial argument as such:
$array1 = array( "berries" => array( "strawberry" => array( "color" => "red", "food" => "desserts"), "dewberry" = array( "color" => "dark violet", "food" => "pies"), );
$array2 = array( "food" => "wine");
$array1["berries"]["dewberry"] = polecat_array_replace($array1["berries"]["dewberry"], $array2);
This is will replace the value for "food" for "dewberry" with "wine".
The function will also do the reverse and add a multi to a single dimensional array or even a 2 tier array to a 5 tier as long as the heirarchy tree is identical.
I hope this helps atleast one person for all that I've gained from this site.
To get exactly same result like in PHP 5.3, the foreach loop in your code should look like:
<?php
...
$count = func_num_args();
for ($i = 1; $i < $count; $i++) {
...
}
...
?>
Check on this code:
<?php
$base = array('id' => NULL, 'login' => NULL, 'credit' => NULL);
$arr1 = array('id' => 2, 'login' => NULL, 'credit' => 5);
$arr2 = array('id' => NULL, 'login' => 'john.doe', 'credit' => 100);
$result = array_replace($base, $arr1, $arr2);
/*
correct output:
array(3) {
"id" => NULL
"login" => string(8) "john.doe"
"credit" => int(100)
}
your output:
array(3) {
"id" => int(2)
"login" => NULL
"credit" => int(5)
}
*/
?>
Function array_replace "replaces elements from passed arrays into the first array" -- this means replace from top-right to first, then from top-right - 1 to first, etc, etc...
a little enhancement to dyer85 at gmail dot com's function below:
<?php
if (!function_exists('array_replace'))
{
function array_replace( array &$array, array &$array1, $filterEmpty=false )
{
$args = func_get_args();
$count = func_num_args()-1;
for ($i = 0; $i < $count; ++$i) {
if (is_array($args[$i])) {
foreach ($args[$i] as $key => $val) {
if ($filterEmpty && empty($val)) continue;
$array[$key] = $val;
}
}
else {
trigger_error(
__FUNCTION__ . '(): Argument #' . ($i+1) . ' is not an array',
E_USER_WARNING
);
return NULL;
}
}
return $array;
}
}
?>
this will allow you to "tetris-like" merge arrays:
<?php
$a= array(
0 => "foo",
1 => "",
2 => "baz"
);
$b= array(
0 => "",
1 => "bar",
2 => ""
);
print_r(array_replace($a,$b, true));
?>
results in:
Array
(
[0] => foo
[1] => bar
[2] => baz
)
For a backward compatible alternative, you might try something like this:
<?php
if (!function_exists('array_replace'))
{
function array_replace( array &$array, array &$array1 )
{
$args = func_get_args();
$count = func_num_args();
for ($i = 0; $i < $count; ++$i) {
if (is_array($args[$i])) {
foreach ($args[$i] as $key => $val) {
$array[$key] = $val;
}
}
else {
trigger_error(
__FUNCTION__ . '(): Argument #' . ($i+1) . ' is not an array',
E_USER_WARNING
);
return NULL;
}
}
return $array;
}
}
?>