Array-Merge on an associative array in PHP

How can i do an array_merge on an associative array, like so:

Array 1:

$options = array (
"1567" => "test",
"1853" => "test1",
);

Array 2:

$option = array (
"none" => "N/A"
);

So i need to array_merge these two but when i do i get this (in debug):

Array
(
    [none] => N/A
    [0] => test
    [1] => test1
)

try using :

$finalArray = $options + $option .see http://codepad.org/BJ0HVtac Just check the behaviour for duplicate keys, I did not test this. For unique keys, it works great.

<?php

$options = array (
                  "1567" => "test",
                  "1853" => "test1",
                  );


$option = array (
"none" => "N/A"
);


$final = array_merge($option,$options);

var_dump($final);


$finalNew = $option + $options ;

var_dump($finalNew);

?>

Just use $options + $option!

var_dump($options + $option);

outputs:

array(3) {
  [1567]=>
  string(4) "test"
  [1853]=>
  string(5) "test1"
  ["none"]=>
  string(3) "N/A"
}

But be careful when there is a key collision. Here is what the PHP manual says:

The keys from the first array will be preserved. If an array key exists in both arrays, then the element from the first array will be used and the matching key's element from the second array will be ignored.

I was looking to merge two associative arrays together, adding the values together if the keys were the same. If there were keys unique to either array, these would be added into the merged array with their existing values.

I couldnt find a function to do this, so made this:

function array_merge_assoc($array1, $array2)
{

    if(sizeof($array1)>sizeof($array2))
    {
        echo $size = sizeof($array1);
    }
    else
    {
        $a = $array1;
        $array1 = $array2;
        $array2 = $a;

        echo $size = sizeof($array1);
    }

    $keys2 = array_keys($array2);

    for($i = 0;$i<$size;$i++)
    {
        $array1[$keys2[$i]] = $array1[$keys2[$i]] + $array2[$keys2[$i]];
    }

    $array1 = array_filter($array1);
    return $array1;
 }

Reference: http://www.php.net/manual/en/function.array-merge.php#90136

Rukmi Patel

$final_option = $option + $options;

when array_merge doesn't work, then simply do

<?php
$new = array();
foreach ($options as $key=>$value) $new[$key] = $value;
foreach ($option as $key=>$value) $new[$key] = $value;
?>

or switch the two foreach loops depending on which array has higher priority

This code could be used for recursive merge:

function merge($arr1, $arr2){
        $out = array();
        foreach($arr1 as $key => $val1){
            if(isset($arr2[$key])){
                if(is_array($arr1[$key]) && is_array($arr2[$key])){
                    $out[$key]=  merge($arr1[$key], $arr2[$key]);
                }else{
                    $out[$key]= array($arr1[$key], $arr2[$key]);
                }
                unset($arr2[$key]);
            }else{
                $out[$key] = $arr1[$key];
            }
        }
        return $out + $arr2;
 }

If arrays having same keys then use array_merge_recursive()

$array1 = array( "a" => "1" , "b" => "45" );

$array2 = array( "a" => "23" , "b" => "33" );

$newarray = array_merge_recursive($array1,$array2);

The array_merge_recursive() wont overwrite, it just makes the value as an array.

来源：https://stackoverflow.com/questions/6813884/array-merge-on-an-associative-array-in-php

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