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Difference between Array merge and Adding array In PHP

This Is all about difference between array merge and adding array in PHP.



1) Array Merge will add two array With re index the key if in case Indexed array
but adding two array is possible for only associative array and it will keep adding without changing the Key of this array.
See the example below in case-1

2) In case if two associative array having same key, then array merge will merge in a single array, But In case adding Two array it will simple over write the index key and merge it. See the example case-2

3) Adding array not work for non-associative array.
See Example Case-3



All Below Example will work for Index key Should be Numeric.

Case-1:

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<?php
$a=array(3=>"red",4=>"green");
$b=array(5=>"blue",6=>"black");
print_r(array_merge($a,$b));
echo "<br/>";
print_r($a+$b);
?>
 
 

Output-:

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Array ( [0] => red [1] => green [2] => blue [3] => black )
Array ( [3] => red [4] => green [5] => blue [6] => black )

Case 2:-

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<?php
$a=array(3=>"red",4=>"green");
$b=array(4=>"blue",6=>"black");
print_r(array_merge($a,$b));
echo "<br/>";
print_r($a+$b);
?>

OutPut:-

 

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Array ( [0] => red [1] => green [2] => blue [3] => black )
Array ( [3] => red [4] => green [6] => black )

Case-3:

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<?php
$a=array("red","green");
$b=array("blue","black");
print_r(array_merge($a,$b));
echo "<br/>";
print_r($a+$b);
?>

Output-:

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Array ( [0] => red [1] => green [2] => blue [3] => black )
Array ( [0] => red [1] => green )

 



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