What potential issues can arise when comparing multidimensional arrays in PHP?

When comparing multidimensional arrays in PHP, a potential issue that can arise is that the built-in comparison operators (like == or ===) may not work as expected due to the nested structure of the arrays. To properly compare multidimensional arrays, you can use the array_diff() function to compare the values of the arrays recursively. 

$array1 = [
    "a" => ["red", "green"],
    "b" => ["blue", "yellow"]
];

$array2 = [
    "a" => ["red", "green"],
    "b" => ["blue", "yellow"]
];

if (array_diff($array1, $array2) || array_diff($array2, $array1)) {
    echo "Arrays are not equal";
} else {
    echo "Arrays are equal";
}

Keywords

multidimensional arrays comparison PHP nested arrays array_diff

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