How to calculate the number of identical values ​​in two arrays in PHP

In PHP development, arrays are a commonly used data structure, and we often need to operate and process arrays. When we need to compare the number of identical elements in two arrays, we can use the array_intersect() function provided by PHP.

array_intersect() function is used to compare the intersection of two or more arrays. It returns an array containing the same values ​​in all arrays. We can obtain the intersection of two arrays by passing them as arguments to this function.

The following is an example of how to use the array_intersect() function to count the number of identical elements in two arrays:

$array1 = array(1, 2, 3, 4, 5);
$array2 = array(4, 5, 6, 7, 8);
$intersection = array_intersect($array1, $array2);
$count = count($intersection);
echo "两个数组中相同元素的个数为：" . $count;

In the above code, we define two arrays $array1 and $array2, they contain some numeric values. We obtain the intersection of these two arrays using the array_intersect() function and store the result in the $intersection variable. Finally, we use the count() function to count the number of elements in the $intersection array and store the result in the $count variable. Finally, we output the number of identical elements.

In addition to using the array_intersect() function, we can also use a loop to count the number of identical elements in two arrays. Here is an example:

$array1 = array(1, 2, 3, 4, 5);
$array2 = array(4, 5, 6, 7, 8);
$count = 0;
foreach ($array1 as $element1) {
    foreach ($array2 as $element2) {
        if ($element1 == $element2) {
            $count++;
        }
    }
}
echo "两个数组中相同元素的个数为：" . $count;

In the above code, we traverse all the elements in the two arrays through two levels of loops, and use if statements to compare whether they are equal. If the two elements are equal, add 1 to the $count variable. Finally, we output the number of identical elements.

The advantage of using the array_intersect() function over loop calculations is that it can handle large arrays more efficiently because it uses a hash table data structure internally to speed up calculations. Additionally, using functions can make your code more concise and easier to understand.

To sum up, when we need to calculate the number of identical elements in two arrays, we can use the array_intersect() function provided by PHP, or we can use a loop to achieve it. Either way, we need to iterate through the array and compare the elements to get the number of identical elements.

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