merge 2 associative arrays if the key is same in PHP code example

Example 1: php combine arrays

$output = array_merge($array1, $array2);

Example 2: array merge in php

/* Array merge is basically use to merge the two array data. */
  
<?php
$a1=array("red","green");
$a2=array("blue","green","yellow");
print_r(array_merge($a1,$a2));
?>
  
/*
Output:
Array ( [0] => red [1] => green [2] => blue [3] => green [4] => yellow )
*/
  
<?php
$a1=array("a"=>"red","b"=>"green");
$a2=array("c"=>"blue","b"=>"yellow");
print_r(array_merge($a1,$a2));
?>

/*
Output:
Array ( [a] => red [b] => yellow [c] => blue )
*/
  
/* In above example you can check the difference in output 
it takes all values of both array in final output, but not in associative array you can check.
because one value gets overwritten by same key reference in both array.
*/