In-depth analysis of the difference between using the plus sign and using array_merge to merge arrays in PHP_PHP Tutorial

$r = array (1,2,3,4,5,6);
$e = array(7,8,9,10);
?>

print_r(array_merge($ r,$e)); // OutputArray ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 )
?>


As you can see from here, array_merge is used to merge arrays. The values ​​in one array are appended to the previous array. Returns the resulting array. If the array contains numeric key names, subsequent values ​​will not overwrite the original values, but will be appended to them. However, use the plus sign to merge arrays. If the key names are the same, the array value that appears first will be taken, and the rest will be ignored
Let’s change the array given earlier

?>

print_r(array_merge($r,$e)); // Output Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [ 8] => 9 )
?>


As you can see from here, array_merge is used to merge arrays. The values ​​in one array are appended to the previous array. If the non-numeric key names are the same, the value of the subsequent array will overwrite the value of the previous array. However, if you use the plus sign to merge arrays, if the key names are the same, the array value that appears first will be taken, and the subsequent ones will be ignored