How to deal with duplicate elements when merging PHP arrays?

When merging arrays in PHP, you can choose the following method to deal with duplicate elements: use array_merge() combined with array_unique() to remove duplicate elements. Use array_replace() to overwrite duplicate elements without changing the original array. Use array_diff() to remove elements from one array that are not in another array.

PHP handles duplicate elements when merging arrays

When merging arrays in PHP, the following methods can be used to handle duplicate elements Method:

1. Use array_merge() combined with array_unique()

This method first uses array_merge() to merge the arrays, and then uses array_unique() Remove duplicate elements.

$array1 = [1, 2, 3, 4, 5];
$array2 = [3, 4, 5, 6, 7];

$merged = array_merge($array1, $array2);
$unique = array_unique($merged);

print_r($unique); // 输出：Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 )

2. Using array_replace()

array_replace() will also overwrite duplicate elements, but will not change the original array.

$array1 = [1, 2, 3, 4, 5];
$array2 = [3, 4, 5, 6, 7];

$replaced = array_replace($array1, $array2);

print_r($replaced); // 输出：Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 )

3. Use array_diff() to remove elements

If you only want to keep elements that are in the first array but not in the second array, you can usearray_diff().

$array1 = [1, 2, 3, 4, 5];
$array2 = [3, 4, 5, 6, 7];

$diff = array_diff($array1, $array2);

print_r($diff); // 输出：Array ( [0] => 1 [1] => 2 )

Practical case

Suppose we have two user shopping carts, each shopping cart contains a set of products. We need to merge these two shopping carts into one shopping cart while handling duplicate products.

$user1Cart = ['item1', 'item2', 'item3'];
$user2Cart = ['item2', 'item3', 'item4'];

$mergedCart = array_merge($user1Cart, $user2Cart);
$uniqueCart = array_unique($mergedCart);

print_r($uniqueCart); // 输出：Array ( [0] => item1 [1] => item2 [2] => item3 [3] => item4 )

By using array_merge() and array_unique(), we merge shopping carts and remove duplicate products.

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