PHP remove duplicate elements from two arrays

In PHP development, removing duplicate array elements is a basic operation. When we have two or more arrays and want to remove duplicate elements from the two arrays and leave non-duplicate elements, we need to use some functions in PHP to achieve this operation.

Below, we will introduce two methods to remove duplicate elements from two arrays.

Method 1: array_unique function

The array_unique function is a function provided by PHP to remove duplicate elements from an array. It can be used to remove identical elements from two arrays.

We can use the array_unique function to merge two arrays and then remove the duplicates. The code is as follows:

$array1 = array('a', 'b', 'b', 'c', 'd');
$array2 = array('c', 'd', 'e');

$merged_array = array_merge($array1, $array2);
$unique_array = array_unique($merged_array);

print_r($unique_array);

In the above code, we define two arrays $array1 and $array2, and then use The array_merge function merges two arrays into a $merged_array array. Next, we use the array_unique function to deduplicate the array and store the result in the $unique_array array. Finally, we use the print_r function to output the deduplicated array content. The result is:

Array
(
    [0] => a
    [1] => b
    [3] => c
    [4] => d
    [5] => e
)

It can be seen that the deduplicated array only contains non-duplicate elements, and the two arrays have been successfully removed. of repeated elements.

Method 2: Loop comparison method

In addition to using the array_unique function, we can also use the loop comparison method to remove duplicate array elements. This method requires using a for or foreach loop to traverse the array, and then determine whether each element has already appeared. If it has already appeared, delete the element.

The following is an example of using the loop comparison method to remove duplicate array elements:

$array1 = array('a', 'b', 'b', 'c', 'd');
$array2 = array('c', 'd', 'e');

foreach ($array1 as $key => $value) {
    if (in_array($value, $array2)) {
        unset($array1[$key]);
    }
}

$merged_array = array_merge($array1, $array2);

print_r($merged_array);

In the above code, we use a foreach loop to traverse each element in the $array1 array. Then, we use the in_array function to determine whether there is already an element equal to the current element in the $array2 array. If it already exists, use the unset function to delete the element. Finally, we use the array_merge function to merge the two arrays into one, and then use the print_r function to output the merged array.

Run the above code, the result is:

Array
(
    [0] => a
    [1] => b
    [3] => d
    [4] => c
    [5] => e
)

You can see that the deduplicated array still contains unique elements, but the order of the array is different from the result of using the array_unique function. .

Summary

In PHP development, removing duplicate elements from two arrays is a basic operation. We can use the array_unique function or loop comparison method to achieve this operation. The array_unique function is a built-in function provided by PHP that can easily remove duplicate elements from an array. The loop comparison method requires the use of a loop method to traverse each element in the array, and use conditional judgment to perform deduplication operations. Both methods have their own advantages and disadvantages, and we can choose to use the appropriate method according to the specific situation.

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