What’s the difference between array_merge() and + when combining arrays?

🔹 array_merge():

• Reindexes numeric keys.
• Overwrites string keys with values from later arrays.

$a = [0 => 'apple', 1 => 'banana'];
$b = [1 => 'orange', 2 => 'grape'];

print_r(array_merge($a, $b));

Result:

[0 => 'apple', 1 => 'orange', 2 => 'grape']

🔹 $a + $b (Union operator):

• Preserves keys from the left-hand array ($a)
• Does not overwrite any existing keys.

$a = [0 => 'apple', 1 => 'banana'];
$b = [1 => 'orange', 2 => 'grape'];

print_r($a + $b);

Result:

[0 => 'apple', 1 => 'banana', 2 => 'grape']

📌 Interview Tip: Use + when merging with preserved keys; use array_merge() when you want values merged and reindexed.