What are the common pitfalls when trying to access and manipulate arrays in PHP?

Common pitfalls when trying to access and manipulate arrays in PHP include not checking if the array key exists before accessing it, not using the correct array functions for manipulation, and not properly handling multidimensional arrays. To avoid these pitfalls, always check if the array key exists before accessing it, use array functions like array_push, array_pop, array_shift, and array_unshift for manipulation, and be mindful of working with multidimensional arrays by using nested loops or array functions like array_map or array_walk.

// Check if array key exists before accessing it
$array = ['key' => 'value'];
if (isset($array['key'])) {
    echo $array['key'];
}

// Using array functions for manipulation
$numbers = [1, 2, 3];
array_push($numbers, 4);
array_pop($numbers);
array_shift($numbers);
array_unshift($numbers, 0);

// Handling multidimensional arrays
$multiArray = [['a', 'b'], ['c', 'd']];
foreach ($multiArray as $subArray) {
    foreach ($subArray as $value) {
        echo $value;
    }
}