What are the potential pitfalls of merging arrays in PHP, particularly when dealing with numeric indices?

When merging arrays with numeric indices in PHP, the main pitfall is that the numeric keys may be re-indexed starting from 0, which can lead to unexpected behavior or data loss. To avoid this issue, you can use the "+" operator to merge arrays, as it preserves the original numeric keys without re-indexing them. 

$array1 = [0 => 'apple', 1 => 'banana'];
$array2 = [2 => 'orange', 3 => 'grape'];

$mergedArray = $array1 + $array2;

print_r($mergedArray);

Keywords

array_merge numeric indices array_combine array_merge_recursive array_replace

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